%!PS-Adobe-2.0
%%Creator: dvipsk 5.58f Copyright 1986, 1994 Radical Eye Software
%%Title: paper.dvi
%%Pages: 6
%%PageOrder: Ascend
%%BoundingBox: 0 0 612 792
%%DocumentFonts: Times-Bold Times-Roman Courier Times-Italic
%%DocumentPaperSizes: Letter
%%EndComments
%DVIPSCommandLine: /pkg/teTeX/bin/dvips.real paper.dvi
%DVIPSParameters: dpi=600, comments removed
%DVIPSSource:  TeX output 1999.05.18:1645
%%BeginProcSet: tex.pro
/TeXDict 250 dict def TeXDict begin /N{def}def /B{bind def}N /S{exch}N
/X{S N}B /TR{translate}N /isls false N /vsize 11 72 mul N /hsize 8.5 72
mul N /landplus90{false}def /@rigin{isls{[0 landplus90{1 -1}{-1 1}
ifelse 0 0 0]concat}if 72 Resolution div 72 VResolution div neg scale
isls{landplus90{VResolution 72 div vsize mul 0 exch}{Resolution -72 div
hsize mul 0}ifelse TR}if Resolution VResolution vsize -72 div 1 add mul
TR[matrix currentmatrix{dup dup round sub abs 0.00001 lt{round}if}
forall round exch round exch]setmatrix}N /@landscape{/isls true N}B
/@manualfeed{statusdict /manualfeed true put}B /@copies{/#copies X}B
/FMat[1 0 0 -1 0 0]N /FBB[0 0 0 0]N /nn 0 N /IE 0 N /ctr 0 N /df-tail{
/nn 8 dict N nn begin /FontType 3 N /FontMatrix fntrx N /FontBBox FBB N
string /base X array /BitMaps X /BuildChar{CharBuilder}N /Encoding IE N
end dup{/foo setfont}2 array copy cvx N load 0 nn put /ctr 0 N[}B /df{
/sf 1 N /fntrx FMat N df-tail}B /dfs{div /sf X /fntrx[sf 0 0 sf neg 0 0]
N df-tail}B /E{pop nn dup definefont setfont}B /ch-width{ch-data dup
length 5 sub get}B /ch-height{ch-data dup length 4 sub get}B /ch-xoff{
128 ch-data dup length 3 sub get sub}B /ch-yoff{ch-data dup length 2 sub
get 127 sub}B /ch-dx{ch-data dup length 1 sub get}B /ch-image{ch-data
dup type /stringtype ne{ctr get /ctr ctr 1 add N}if}B /id 0 N /rw 0 N
/rc 0 N /gp 0 N /cp 0 N /G 0 N /sf 0 N /CharBuilder{save 3 1 roll S dup
/base get 2 index get S /BitMaps get S get /ch-data X pop /ctr 0 N ch-dx
0 ch-xoff ch-yoff ch-height sub ch-xoff ch-width add ch-yoff
setcachedevice ch-width ch-height true[1 0 0 -1 -.1 ch-xoff sub ch-yoff
.1 sub]{ch-image}imagemask restore}B /D{/cc X dup type /stringtype ne{]}
if nn /base get cc ctr put nn /BitMaps get S ctr S sf 1 ne{dup dup
length 1 sub dup 2 index S get sf div put}if put /ctr ctr 1 add N}B /I{
cc 1 add D}B /bop{userdict /bop-hook known{bop-hook}if /SI save N @rigin
0 0 moveto /V matrix currentmatrix dup 1 get dup mul exch 0 get dup mul
add .99 lt{/QV}{/RV}ifelse load def pop pop}N /eop{SI restore userdict
/eop-hook known{eop-hook}if showpage}N /@start{userdict /start-hook
known{start-hook}if pop /VResolution X /Resolution X 1000 div /DVImag X
/IE 256 array N 0 1 255{IE S 1 string dup 0 3 index put cvn put}for
65781.76 div /vsize X 65781.76 div /hsize X}N /p{show}N /RMat[1 0 0 -1 0
0]N /BDot 260 string N /rulex 0 N /ruley 0 N /v{/ruley X /rulex X V}B /V
{}B /RV statusdict begin /product where{pop product dup length 7 ge{0 7
getinterval dup(Display)eq exch 0 4 getinterval(NeXT)eq or}{pop false}
ifelse}{false}ifelse end{{gsave TR -.1 .1 TR 1 1 scale rulex ruley false
RMat{BDot}imagemask grestore}}{{gsave TR -.1 .1 TR rulex ruley scale 1 1
false RMat{BDot}imagemask grestore}}ifelse B /QV{gsave newpath transform
round exch round exch itransform moveto rulex 0 rlineto 0 ruley neg
rlineto rulex neg 0 rlineto fill grestore}B /a{moveto}B /delta 0 N /tail
{dup /delta X 0 rmoveto}B /M{S p delta add tail}B /b{S p tail}B /c{-4 M}
B /d{-3 M}B /e{-2 M}B /f{-1 M}B /g{0 M}B /h{1 M}B /i{2 M}B /j{3 M}B /k{
4 M}B /w{0 rmoveto}B /l{p -4 w}B /m{p -3 w}B /n{p -2 w}B /o{p -1 w}B /q{
p 1 w}B /r{p 2 w}B /s{p 3 w}B /t{p 4 w}B /x{0 S rmoveto}B /y{3 2 roll p
a}B /bos{/SS save N}B /eos{SS restore}B end
%%EndProcSet
%%BeginFont: Times-Bold
% @@psencodingfile@{
%   author = "S. Rahtz, P. MacKay, Alan Jeffrey, B. Horn, K. Berry",
%   version = "0.6",
%   date = "22 June 1996",
%   filename = "8r.enc",
%   email = "kb@@mail.tug.org",
%   address = "135 Center Hill Rd. // Plymouth, MA 02360",
%   codetable = "ISO/ASCII",
%   checksum = "119     662    4424",
%   docstring = "Encoding for TrueType or Type 1 fonts to be used with TeX."
% @}
% 
% Idea is to have all the characters normally included in Type 1 fonts
% available for typesetting. This is effectively the characters in Adobe
% Standard Encoding + ISO Latin 1 + extra characters from Lucida.
% 
% Character code assignments were made as follows:
% 
% (1) the Windows ANSI characters are almost all in their Windows ANSI
% positions, because some Windows users cannot easily reencode the
% fonts, and it makes no difference on other systems. The only Windows
% ANSI characters not available are those that make no sense for
% typesetting -- rubout (127 decimal), nobreakspace (160), softhyphen
% (173). quotesingle and grave are moved just because it's such an
% irritation not having them in TeX positions.
% 
% (2) Remaining characters are assigned arbitrarily to the lower part
% of the range, avoiding 0, 10 and 13 in case we meet dumb software.
% 
% (3) Y&Y Lucida Bright includes some extra text characters; in the
% hopes that other PostScript fonts, perhaps created for public
% consumption, will include them, they are included starting at 0x12.
% 
% (4) Remaining positions left undefined are for use in (hopefully)
% upward-compatible revisions, if someday more characters are generally
% available.
% 
% (5) hyphen appears twice for compatibility with both ASCII and Windows.
% 
/TeXBase1Encoding [
% 0x00 (encoded characters from Adobe Standard not in Windows 3.1)
  /.notdef /dotaccent /fi /fl
  /fraction /hungarumlaut /Lslash /lslash
  /ogonek /ring /.notdef
  /breve /minus /.notdef 
% These are the only two remaining unencoded characters, so may as
% well include them.
  /Zcaron /zcaron 
% 0x10
 /caron /dotlessi 
% (unusual TeX characters available in, e.g., Lucida Bright)
 /dotlessj /ff /ffi /ffl 
 /.notdef /.notdef /.notdef /.notdef
 /.notdef /.notdef /.notdef /.notdef
 % very contentious; it's so painful not having quoteleft and quoteright
 % at 96 and 145 that we move the things normally found there down to here.
 /grave /quotesingle 
% 0x20 (ASCII begins)
 /space /exclam /quotedbl /numbersign
 /dollar /percent /ampersand /quoteright
 /parenleft /parenright /asterisk /plus /comma /hyphen /period /slash
% 0x30
 /zero /one /two /three /four /five /six /seven
 /eight /nine /colon /semicolon /less /equal /greater /question
% 0x40
 /at /A /B /C /D /E /F /G /H /I /J /K /L /M /N /O
% 0x50
 /P /Q /R /S /T /U /V /W
 /X /Y /Z /bracketleft /backslash /bracketright /asciicircum /underscore
% 0x60
 /quoteleft /a /b /c /d /e /f /g /h /i /j /k /l /m /n /o
% 0x70
 /p /q /r /s /t /u /v /w
 /x /y /z /braceleft /bar /braceright /asciitilde
 /.notdef % rubout; ASCII ends
% 0x80
 /.notdef /.notdef /quotesinglbase /florin
 /quotedblbase /ellipsis /dagger /daggerdbl
 /circumflex /perthousand /Scaron /guilsinglleft
 /OE /.notdef /.notdef /.notdef
% 0x90
 /.notdef /.notdef /.notdef /quotedblleft
 /quotedblright /bullet /endash /emdash
 /tilde /trademark /scaron /guilsinglright
 /oe /.notdef /.notdef /Ydieresis
% 0xA0
 /.notdef % nobreakspace
 /exclamdown /cent /sterling
 /currency /yen /brokenbar /section
 /dieresis /copyright /ordfeminine /guillemotleft
 /logicalnot
 /hyphen % Y&Y (also at 45); Windows' softhyphen
 /registered
 /macron
% 0xD0
 /degree /plusminus /twosuperior /threesuperior
 /acute /mu /paragraph /periodcentered
 /cedilla /onesuperior /ordmasculine /guillemotright
 /onequarter /onehalf /threequarters /questiondown
% 0xC0
 /Agrave /Aacute /Acircumflex /Atilde /Adieresis /Aring /AE /Ccedilla
 /Egrave /Eacute /Ecircumflex /Edieresis
 /Igrave /Iacute /Icircumflex /Idieresis
% 0xD0
 /Eth /Ntilde /Ograve /Oacute
 /Ocircumflex /Otilde /Odieresis /multiply
 /Oslash /Ugrave /Uacute /Ucircumflex
 /Udieresis /Yacute /Thorn /germandbls
% 0xE0
 /agrave /aacute /acircumflex /atilde
 /adieresis /aring /ae /ccedilla
 /egrave /eacute /ecircumflex /edieresis
 /igrave /iacute /icircumflex /idieresis
% 0xF0
 /eth /ntilde /ograve /oacute
 /ocircumflex /otilde /odieresis /divide
 /oslash /ugrave /uacute /ucircumflex
 /udieresis /yacute /thorn /ydieresis
] def
%%EndFont
%%BeginProcSet: texps.pro
TeXDict begin /rf{findfont dup length 1 add dict begin{1 index /FID ne 2
index /UniqueID ne and{def}{pop pop}ifelse}forall[1 index 0 6 -1 roll
exec 0 exch 5 -1 roll VResolution Resolution div mul neg 0 0]/Metrics
exch def dict begin Encoding{exch dup type /integertype ne{pop pop 1 sub
dup 0 le{pop}{[}ifelse}{FontMatrix 0 get div Metrics 0 get div def}
ifelse}forall Metrics /Metrics currentdict end def[2 index currentdict
end definefont 3 -1 roll makefont /setfont load]cvx def}def
/ObliqueSlant{dup sin S cos div neg}B /SlantFont{4 index mul add}def
/ExtendFont{3 -1 roll mul exch}def /ReEncodeFont{/Encoding exch def}def
end
%%EndProcSet
%%BeginProcSet: special.pro
TeXDict begin /SDict 200 dict N SDict begin /@SpecialDefaults{/hs 612 N
/vs 792 N /ho 0 N /vo 0 N /hsc 1 N /vsc 1 N /ang 0 N /CLIP 0 N /rwiSeen
false N /rhiSeen false N /letter{}N /note{}N /a4{}N /legal{}N}B
/@scaleunit 100 N /@hscale{@scaleunit div /hsc X}B /@vscale{@scaleunit
div /vsc X}B /@hsize{/hs X /CLIP 1 N}B /@vsize{/vs X /CLIP 1 N}B /@clip{
/CLIP 2 N}B /@hoffset{/ho X}B /@voffset{/vo X}B /@angle{/ang X}B /@rwi{
10 div /rwi X /rwiSeen true N}B /@rhi{10 div /rhi X /rhiSeen true N}B
/@llx{/llx X}B /@lly{/lly X}B /@urx{/urx X}B /@ury{/ury X}B /magscale
true def end /@MacSetUp{userdict /md known{userdict /md get type
/dicttype eq{userdict begin md length 10 add md maxlength ge{/md md dup
length 20 add dict copy def}if end md begin /letter{}N /note{}N /legal{}
N /od{txpose 1 0 mtx defaultmatrix dtransform S atan/pa X newpath
clippath mark{transform{itransform moveto}}{transform{itransform lineto}
}{6 -2 roll transform 6 -2 roll transform 6 -2 roll transform{
itransform 6 2 roll itransform 6 2 roll itransform 6 2 roll curveto}}{{
closepath}}pathforall newpath counttomark array astore /gc xdf pop ct 39
0 put 10 fz 0 fs 2 F/|______Courier fnt invertflag{PaintBlack}if}N
/txpose{pxs pys scale ppr aload pop por{noflips{pop S neg S TR pop 1 -1
scale}if xflip yflip and{pop S neg S TR 180 rotate 1 -1 scale ppr 3 get
ppr 1 get neg sub neg ppr 2 get ppr 0 get neg sub neg TR}if xflip yflip
not and{pop S neg S TR pop 180 rotate ppr 3 get ppr 1 get neg sub neg 0
TR}if yflip xflip not and{ppr 1 get neg ppr 0 get neg TR}if}{noflips{TR
pop pop 270 rotate 1 -1 scale}if xflip yflip and{TR pop pop 90 rotate 1
-1 scale ppr 3 get ppr 1 get neg sub neg ppr 2 get ppr 0 get neg sub neg
TR}if xflip yflip not and{TR pop pop 90 rotate ppr 3 get ppr 1 get neg
sub neg 0 TR}if yflip xflip not and{TR pop pop 270 rotate ppr 2 get ppr
0 get neg sub neg 0 S TR}if}ifelse scaleby96{ppr aload pop 4 -1 roll add
2 div 3 1 roll add 2 div 2 copy TR .96 dup scale neg S neg S TR}if}N /cp
{pop pop showpage pm restore}N end}if}if}N /normalscale{Resolution 72
div VResolution 72 div neg scale magscale{DVImag dup scale}if 0 setgray}
N /psfts{S 65781.76 div N}N /startTexFig{/psf$SavedState save N userdict
maxlength dict begin /magscale true def normalscale currentpoint TR
/psf$ury psfts /psf$urx psfts /psf$lly psfts /psf$llx psfts /psf$y psfts
/psf$x psfts currentpoint /psf$cy X /psf$cx X /psf$sx psf$x psf$urx
psf$llx sub div N /psf$sy psf$y psf$ury psf$lly sub div N psf$sx psf$sy
scale psf$cx psf$sx div psf$llx sub psf$cy psf$sy div psf$ury sub TR
/showpage{}N /erasepage{}N /copypage{}N /p 3 def @MacSetUp}N /doclip{
psf$llx psf$lly psf$urx psf$ury currentpoint 6 2 roll newpath 4 copy 4 2
roll moveto 6 -1 roll S lineto S lineto S lineto closepath clip newpath
moveto}N /endTexFig{end psf$SavedState restore}N /@beginspecial{SDict
begin /SpecialSave save N gsave normalscale currentpoint TR
@SpecialDefaults count /ocount X /dcount countdictstack N}N /@setspecial
{CLIP 1 eq{newpath 0 0 moveto hs 0 rlineto 0 vs rlineto hs neg 0 rlineto
closepath clip}if ho vo TR hsc vsc scale ang rotate rwiSeen{rwi urx llx
sub div rhiSeen{rhi ury lly sub div}{dup}ifelse scale llx neg lly neg TR
}{rhiSeen{rhi ury lly sub div dup scale llx neg lly neg TR}if}ifelse
CLIP 2 eq{newpath llx lly moveto urx lly lineto urx ury lineto llx ury
lineto closepath clip}if /showpage{}N /erasepage{}N /copypage{}N newpath
}N /@endspecial{count ocount sub{pop}repeat countdictstack dcount sub{
end}repeat grestore SpecialSave restore end}N /@defspecial{SDict begin}
N /@fedspecial{end}B /li{lineto}B /rl{rlineto}B /rc{rcurveto}B /np{
/SaveX currentpoint /SaveY X N 1 setlinecap newpath}N /st{stroke SaveX
SaveY moveto}N /fil{fill SaveX SaveY moveto}N /ellipse{/endangle X
/startangle X /yrad X /xrad X /savematrix matrix currentmatrix N TR xrad
yrad scale 0 0 1 startangle endangle arc savematrix setmatrix}N end
%%EndProcSet
TeXDict begin 40258431 52099146 1000 600 600 (paper.dvi)
@start /Fa 2 117 df<00F800000FF000000FF0000000F0000000F0000001E0000001E0
000001E0000001E0000003C0000003C0000003C0000003C000000787E000079FF80007B8
3C0007E01C000FC01E000F801E000F801E000F001E001E003C001E003C001E003C001E00
78003C0078003C0078003C00F0203C00F0307800F0607801E0607801E0C07801E0C0F000
E380F000FF0060003C001C247CA224>104 D<00300000780000F00000F00000F00000F0
0001E00001E00001E00001E00003C000FFFF80FFFF8003C0000780000780000780000780
000F00000F00000F00000F00001E00001E00001E01001E01803C03003C06003C06003C0C
001C38000FF00007C00011217D9F18>116 D E /Fb 186[50 1[50
67[{TeXBase1Encoding ReEncodeFont}2 83.333336 /Courier
rf /Fc 87[25 19[42 42 24[29 33 33 50 33 37 21 29 29 1[37
37 37 54 21 33 21 21 37 37 21 33 37 33 37 37 7[42 3[54
42 37 46 54 46 54 50 62 42 1[33 25 1[54 46 46 54 50 1[46
6[25 37 37 37 37 37 1[37 37 37 2[19 25 19 41[37 2[{
TeXBase1Encoding ReEncodeFont}60 75.000000 /Times-Italic
rf /Fd 205[25 25 49[{TeXBase1Encoding ReEncodeFont}2
50.000000 /Times-Roman rf /Fe 205[29 29 49[{
TeXBase1Encoding ReEncodeFont}2 58.333336 /Times-Roman
rf /Ff 107[46 46 25[37 1[55 37 42 23 32 32 2[42 42 60
23 37 1[23 42 42 23 37 42 37 42 42 7[46 4[46 5[55 69
9[55 20[21 1[21 44[{TeXBase1Encoding ReEncodeFont}30
83.333336 /Times-Italic rf /Fg 135[37 2[42 25 29 33 1[42
37 42 62 21 2[21 42 37 25 33 42 33 42 37 12[50 1[54 3[54
71 50 58 1[29 58 1[46 50 54 54 1[54 6[25 37 37 37 1[37
37 1[37 37 37 1[19 25 3[25 25 37[42 2[{TeXBase1Encoding ReEncodeFont}46
75.000000 /Times-Bold rf /Fh 135[50 1[50 55 33 39 44
1[55 50 55 83 28 55 1[28 55 50 33 44 55 44 55 50 9[100
2[66 55 72 1[61 6[39 1[78 61 66 72 72 1[72 65[{
TeXBase1Encoding ReEncodeFont}33 100.000000 /Times-Bold
rf /Fi 75[25 29[37 27[33 37 37 54 37 37 21 29 25 37 37
37 37 58 21 37 21 21 37 37 25 33 37 33 37 33 6[46 54
54 71 54 54 46 42 50 54 42 54 54 66 46 54 29 25 54 54
42 46 54 50 50 54 5[21 21 37 37 37 37 37 37 37 37 37
37 21 19 25 19 2[25 25 25 58 62 33[42 42 2[{
TeXBase1Encoding ReEncodeFont}77 75.000000 /Times-Roman
rf /Fj 134[42 1[60 1[46 28 32 37 2[42 46 69 23 46 1[23
46 42 28 37 46 37 46 42 13[46 5[78 55 7[60 1[55 60 18[21
4[28 28 40[{TeXBase1Encoding ReEncodeFont}29 83.333336
/Times-Bold rf /Fk 134[45 3[45 45 45 45 1[45 45 45 45
45 2[45 3[45 45 45 45 33[45 17[45 46[{TeXBase1Encoding ReEncodeFont}17
75.000000 /Courier rf /Fl 105[42 1[37 37 24[37 42 42
60 42 42 23 32 28 42 42 42 42 65 23 42 23 23 42 42 28
37 42 37 42 37 7[60 60 78 60 60 51 46 55 1[46 60 60 74
51 60 32 28 60 60 46 51 60 55 55 60 5[23 23 42 42 42
42 42 42 42 42 42 42 1[21 28 21 2[28 28 28 65 69 33[46
46 2[{TeXBase1Encoding ReEncodeFont}75 83.333336 /Times-Roman
rf /Fm 134[45 3[51 30 1[40 2[45 51 1[25 2[25 51 2[40
1[40 51 45 13[51 5[86 1[71 4[56 2[66 20[23 46[{
TeXBase1Encoding ReEncodeFont}19 91.249977 /Times-Bold
rf /Fn 134[60 3[66 40 47 53 2[60 66 100 33 66 1[33 1[60
1[53 66 53 66 60 12[80 66 2[73 8[93 2[86 1[80 86 6[40
58[{TeXBase1Encoding ReEncodeFont}25 119.999947 /Times-Bold
rf end
%%EndProlog
%%BeginSetup
%%Feature: *Resolution 600dpi
TeXDict begin
%%PaperSize: Letter
%%EndSetup
%%Page: 1 1
1 0 bop -66 277 a Fn(T)-11 b(aking)31 b(T)n(ime)e(to)g(Structur)n(e)j
(Discourse:)k(Pr)n(onoun)31 b(Generation)g(Bey)m(ond)f(Accessibility)
675 515 y Fm(Kathleen)23 b(F)-10 b(.)22 b(McCoy)303 615
y Fl(Dept.)e(of)g(Computer)f(and)g(Information)f(Sciences)663
715 y(Uni)n(v)o(ersity)h(of)h(Dela)o(w)o(are)796 814
y(103)g(Smith)g(Hall)626 914 y(Ne)n(w)o(ark,)f(DE)i(19716,)d(USA)647
1013 y Fk(mccoy@cis.udel.edu)2551 515 y Fm(Michael)24
b(Strube)2138 615 y Fl(Institute)c(for)f(Research)h(in)h(Cogniti)n(v)o
(e)e(Science)2401 715 y(Uni)n(v)o(ersity)g(of)h(Pennsylv)n(ania)2322
814 y(3401)f(W)-7 b(alnut)20 b(Street,)g(Suite)h(400A)2355
914 y(Philadelphia,)d(P)-8 b(A)21 b(19104,)d(USA)2290
1013 y Fk(strube@linc.cis.upenn.edu)708 1283 y Fj(Abstract)-67
1469 y Fi(In)i(order)h(to)f(produce)i(coherent)f(te)o(xt,)f(natural)h
(language)h(generation)-67 1543 y(systems)h(must)f(ha)o(v)o(e)h(the)g
(ability)f(to)g(generate)h(pronouns)i(in)d(the)h(ap-)-67
1618 y(propriate)e(places.)30 b(In)21 b(the)g(past,)g(pronoun)i(usage)f
(w)o(as)f(primarily)g(in-)-67 1693 y(v)o(estigated)k(with)g(respect)g
(to)g(the)g(accessibility)g(of)h(referents.)41 b(That)-67
1768 y(is,)24 b(it)f(w)o(as)h(assumed)h(that)e(a)g(pronoun)j(should)f
(be)e(generated)i(when-)-67 1842 y(e)n(v)o(er)f(the)h(referent)f(w)o
(as)g(suf)n(\002ciently)g(accessible)h(so)f(as)g(to)g(mak)o(e)h(its)-67
1917 y(resolution)h(easy)-5 b(.)43 b(W)-6 b(e)24 b(found)j(that)e(such)
h(an)f(e)o(xplanation)i(does)e(not)-67 1992 y(seem)d(to)g(account)h
(well)e(for)h(the)f(patterns)i(of)e(pronoun)j(usage)f(found)-67
2067 y(in)e(naturally)g(occurring)h(te)o(xts.)30 b(W)-6
b(e)20 b(present)i(an)f(algorithm)g(for)g(gen-)-67 2141
y(erating)e(appropriate)g(anaphoric)g(e)o(xpressions)h(which)f(tak)o
(es)f(into)h(ac-)-67 2216 y(count)e(the)g(temporal)g(structure)f(of)h
(te)o(xts)f(\(as)g(a)h(discourse)g(structuring)-67 2291
y(de)n(vice\))24 b(and)g(kno)n(wledge)g(about)g(ambiguous)h(conte)o
(xts.)36 b(Other)23 b(im-)-67 2365 y(portant)k(f)o(actors)g(in)g(our)g
(algorithm)g(are)g(sentence)h(boundaries)g(and)-67 2440
y(the)19 b(distance)h(from)g(the)f(last)g(mention)h(of)f(the)h(anaphor)
l(.)25 b(W)-6 b(e)19 b(back)h(up)-67 2515 y(our)f(hypotheses)i(with)d
(some)i(empirical)e(results)h(indicating)h(that)e(our)-67
2590 y(algorithm)i(chooses)g(the)f(right)h(referring)f(e)o(xpression)h
(in)f(85\045)h(of)g(the)-67 2664 y(cases.)592 2943 y
Fh(Intr)n(oduction)-150 3074 y Fl(Anaphoric)e(e)o(xpressions)g(are)i
(an)f(important)g(component)e(to)j(gener)n(-)-150 3166
y(ating)25 b(coherent)f(discourses.)41 b(While)26 b(there)f(has)h(been)
f(some)g(w)o(ork)-150 3257 y(on)j(generating)e(appropriate)g(referring)
g(e)o(xpressions,)j(little)g(atten-)-150 3348 y(tion)19
b(has)h(been)f(gi)n(v)o(en)f(to)i(the)f(problem)f(of)h(when)g(a)h
(pronoun)d(should)-150 3439 y(be)f(used)g(to)g(refer)g(to)g(an)g
(object.)23 b(In)16 b(most)g(instances)h(the)f(assumption)-150
3531 y(has)g(been)f(that)h(a)g(pronoun)d(should)h(be)i(generated)e
(when)h(referring)e(to)-150 3622 y(a)18 b(discourse)f(entity)g(that)h
(is)h(highly)d(prominent)g(\(accessible\).)23 b(Ho)n(w-)-150
3713 y(e)n(v)o(er)m(,)i(a)g(study)g(of)g(naturally)e(occurring)g(te)o
(xts)i(re)n(v)o(eals)g(that)g(f)o(actors)-150 3805 y(be)o(yond)h
(accessibility)j(must)f(be)g(tak)o(en)g(into)h(account)e(in)h(order)f
(to)-150 3896 y(e)o(xplain)19 b(the)h(patterns)g(of)g(pronoun)d(use)k
(found.)-67 3992 y(In)16 b(this)h(paper)e(we)h(attempt)g(to)h(in)m(v)o
(estigate)d(f)o(actors)i(that)g(might)g(in-)-150 4084
y(\003uence)22 b(the)g(use)h(of)f(pronominal)e(reference)g(forms.)31
b(In)22 b(particular)m(,)-150 4175 y(we)27 b(attempt)e(to)i(answer)f
(the)g(question)f(of)h(when)g(it)h(is)g(appropriate)-150
4266 y(to)c(generate)f(a)i(pronoun)c(v)o(ersus)j(some)g(other)f(kind)g
(of)h(de\002nite)g(de-)-150 4358 y(scription)i(\(i.e.,)j(a)e
(de\002nite)g(noun)f(phrase)g(or)h(proper)f(name\))g(when)-150
4449 y(realizing)c(an)i(anaphoric)d(e)o(xpression.)30
b(Pronouns)20 b(are)j(pre)n(v)n(alent)d(in)-150 4540
y(te)o(xt)f(and)g(play)g(a)h(role)f(in)g(te)o(xt)g(coherence,)f(yet)h
(pronoun)e(generation)-150 4632 y(has)25 b(gotten)e(v)o(ery)h(little)h
(attention.)37 b(T)-7 b(o)25 b(date)f(most)h(of)f(the)g(research)-150
4723 y(in)m(v)n(olving)14 b(pronouns)g(in)i(te)o(xt)g(has)g
(concentrated)e(on)h(the)i(problem)d(of)-150 4814 y(pronoun)19
b(resolution)i(\(needed)f(for)h(natural)g(language)f(understand-)-150
4906 y(ing\).)44 b(While)27 b(it)g(is)h(lik)o(ely)e(that)h(the)g(w)o
(ork)f(on)g(pronoun)e(resolution)-150 4997 y(may)j(be)h(rele)n(v)n(ant)
e(to)i(the)g(problem)e(of)h(pronoun)e(generation)g(\(one)-150
5088 y(w)o(ould)h(not)h(w)o(ant)g(to)g(generate)e(a)j(pronoun)c(that)j
(the)g(reader)f(could)-150 5180 y(not)31 b(resolv)o(e)g(with)h
(reasonable)e(ef)n(fort\),)j(additional)e(e)o(xplanations)-150
5271 y(are)20 b(needed.)-67 5367 y(Our)29 b(tack)g(has)g(been)f(to)i
(study)e(naturally)g(occurring)f(e)o(xamples)-150 5459
y(and)18 b(to)g(try)g(to)g(hypothesize)e(rules)i(that)g(e)o(xplain)f
(the)h(pronoun)d(use)j(in)-150 5550 y(those)25 b(e)o(xamples.)38
b(T)-7 b(o)25 b(date)g(we)g(ha)n(v)o(e)g(concentrated)d(our)j(study)f
(on)2025 1283 y(Ne)n(w)f(Y)-9 b(ork)23 b(T)m(imes)g(ne)n(ws)g
(articles.)34 b(W)-7 b(e)25 b(hope)d(to)h(generalize)f(some)2025
1374 y(of)e(our)f(\002ndings)h(to)g(other)f(types)h(of)g(te)o(xt)g
(genres)g(as)h(well.)2108 1468 y(Consider)g(the)i(follo)n(wing)d
(passage)i(from)f(the)h(\002rst)h(se)n(v)o(eral)e(lines)2025
1560 y(of)f(one)g(of)f(the)i(stories)f(we)h(analyzed:)2108
1722 y Fg(Example)e(1:)2233 1799 y Fi(When)31 b Fg(K)n(enneth)f(L.)h
(Curtis)g Fi(w)o(as)g(wheeled)h(into)g(court)f(nine)2108
1874 y(years)g(ago,)k(mute,)e(dull-e)o(yed)f(and)g(crippled,)i(it)c
(seemed)i(clear)f(to)2108 1948 y(nearly)20 b(e)n(v)o(eryone)h(in)m(v)o
(olv)o(ed)f(that)f(it)g(w)o(ould)h(be)g(pointless)g(to)f(put)g
Fg(him)2108 2023 y Fi(on)g(trial)f(for)g(the)g(murder)h(of)g
Fg(his)e Fi(former)i(girlfriend,)f(Donna)i(Kalson,)2108
2098 y(and)g(the)f(w)o(ounding)h(of)f(her)g(companion.)2233
2175 y(It)30 b(had)i(been)g(a)f(year)g(since)g Fg(Mr)-7
b(.)59 b(Curtis)30 b Fi(had)i(slammed)g Fg(his)2108 2250
y Fi(pickup)20 b(truck)e(into)h(them,)f(breaking)i(their)e(le)o(gs.)23
b Fg(He)c Fi(then)g(shot)g(them)2108 2325 y(both)24 b(and,)h(\002nally)
-5 b(,)24 b(\002red)f(a)g(b)o(ullet)g(into)h Fg(his)e
Fi(o)n(wn)i(brain.)37 b Fg(Mr)-7 b(.)35 b(Cur)m(-)2108
2399 y(tis)26 b Fi(lingered)g(in)g(a)g(coma)h(for)f(months,)i(then)f(a)
o(w)o(ok)o(e)g(to)f(a)g(w)o(orld)h(of)2108 2474 y(paralysis,)h(pain)f
(and)g(mental)f(confusion)i(from)e(which)h(psychiatric)2108
2549 y(e)o(xperts)19 b(said)g Fg(he)g Fi(w)o(ould)h(ne)n(v)o(er)f(emer)
o(ge.)2233 2626 y(One)g(e)o(xpert)g(calculated)h Fg(his)e
Fi(I.Q.)g(at)g(62.....)2108 2802 y Fl(F)o(or)30 b(con)m(v)o(enience,)g
(we)h(ha)n(v)o(e)f(indicated)f(all)j(references)d(to)i(the)2025
2893 y(main)20 b(character)f(in)h(bold.)2108 2987 y(A)32
b(surprising)f(thing)g(to)h(note)f(about)g(this)h(passage)f(is)i(that)f
(not)2025 3079 y(all)i(of)f(the)h(anaphoric)e(references)g(to)i
Ff(Mr)-9 b(.)34 b(Curtis)g Fl(are)g(pronouns)2025 3170
y(e)n(v)o(en)29 b(though)g(he)h(is)h(ar)o(guably)d(the)i(focus)g(of)g
(e)n(v)o(ery)f(sentence)h(in-)2025 3261 y(cluded.)j(Pre)n(vious)22
b(w)o(ork)h(on)f(pronoun)f(generation)g(w)o(ould)h(predict)2025
3353 y(that)30 b(a)h(pronoun)c(should)i(be)h(used)g(if)g(the)g(same)h
(item)f(remains)f(in)2025 3444 y(focus.)43 b(Thus)26
b(it)i(appears)d(that)i(something)e(other)g(than)h(a)h(straight-)2025
3535 y(forw)o(ard)e(application)g(of)i(focusing)e(or)h(other)g(pronoun)
e(resolution)2025 3627 y(algorithms)19 b(is)i(necessary)-5
b(.)2108 3721 y(A)26 b(second)f(thing)h(to)g(note)f(about)g(this)h
(passage)g(is)h(that)f(the)g(sen-)2025 3812 y(tences)20
b(are)g(generally)e(long)h(and)g(comple)o(x)g(and)g(often)g(contain)g
(se)n(v-)2025 3903 y(eral)32 b(references)f(to)h(the)g(same)g
(character)-5 b(.)59 b(These)32 b(types)g(of)g(sen-)2025
3995 y(tences)d(are)h(v)o(ery)e(dif)n(ferent)g(from)g(those)h(that)h
(ha)n(v)o(e)f(been)g(consid-)2025 4086 y(ered)e(by)h(an)o(y)f
(generation)f(system)i(that)g(has)g(rules)f(for)h(generating)2025
4177 y(pronouns.)46 b(In)27 b(addition,)h(it)h(is)g(not)e(clear)h(ho)n
(w)g(most)f(focusing)g(or)2025 4269 y(pronoun)17 b(interpretation)i
(algorithms)f(w)o(ould)i(handle)f(them.)2108 4363 y(Looking)f(for)h(an)
h(e)o(xplanation,)d(one)i(might)h(turn)f(to)h(the)g(underly-)2025
4454 y(ing)j(structure)f(of)g(the)h(te)o(xt.)34 b(Ho)n(we)n(v)o(er)m(,)
21 b(in)i(doing)f(so,)i(care)f(must)g(be)2025 4545 y(tak)o(en)18
b(to)h(ensure)f(that)h(the)g(chosen)f(structure)g(both)g(af)n(fects)g
(pronoun)2025 4637 y(generation)33 b(decisions)i(and)f(is)i(something)e
(that)h(is)h(well-de\002ned)2025 4728 y(from)25 b(a)h(generation)d
(perspecti)n(v)o(e.)40 b(A)26 b(structuring)e(de)n(vice)g(such)i(as)
2025 4819 y(paragraph)e(breaks)j(f)o(ails)g(on)g(both)f(of)h(these)g
(counts.)45 b(At)27 b(\002rst)h(one)2025 4911 y(might)22
b(e)o(xpect)f(to)h(see)h(a)g(de\002nite)f(description)f(at)i(the)f(be)o
(ginning)e(of)2025 5002 y(a)g(paragraph,)d(and)h(a)i(pronoun)d(inside)i
(a)h(paragraph)d(\(as)j(long)e(as)j(the)2025 5093 y(item)k(being)e
(referred)g(to)i(is)h(in)f(focus\).)37 b(While)25 b(this)g(correctly)e
(pre-)2025 5185 y(dicts)18 b(the)f(name)g(at)h(the)f(be)o(ginning)e(of)
i(paragraph)e(tw)o(o,)j(notice)f(there)2025 5276 y(is)i(a)g(name)f(in)g
(the)h(middle)e(of)h(that)g(same)h(paragraph)d(and)i(a)g(pronoun)2025
5367 y(at)24 b(the)f(be)o(ginning)d(of)j(paragraph)e(three.)33
b(More)22 b(importantly)-5 b(,)22 b(from)2025 5459 y(the)29
b(perspecti)n(v)o(e)f(of)g(a)i(generation)d(system,)32
b(it)d(is)h(not)f(at)h(all)g(clear)2025 5550 y(ho)n(w)f(a)h(paragraph)d
(break)i(should)f(be)i(de\002ned.)52 b(Thus)29 b(positing)g(a)p
eop
%%Page: 2 2
2 1 bop -150 83 a Fl(rule)30 b(based)g(on)g(such)g(a)h(structuring)d
(de)n(vice)i(is)h(not)f(helpful.)54 b(W)-7 b(e)-150 174
y(must)31 b(search)f(for)g(an)g(answer)g(that)h(\(1\))f(e)o(xplains)f
(the)i(patterns)f(of)-150 266 y(pronouns)23 b(found)i(in)h(naturally)e
(occurring)g(te)o(xt,)j(and)e(\(2\))g(is)i(based)-150
357 y(on)20 b(information)e(a)n(v)n(ailable)h(to)i(a)f(sentence)g
(generation)e(system.)-67 448 y(In)g(this)h(paper)f(we)g(present)g(our)
g(preliminary)e(w)o(ork)i(in)h(doing)e(just)-150 540
y(that.)43 b(Our)25 b(w)o(ork)h(so)g(f)o(ar)g(has)g(led)g(us)h(to)f
(hypothesize)d(se)n(v)o(eral)j(f)o(ac-)-150 631 y(tors)21
b(that)h(af)n(fect)f(pronoun)d(generation)h(and)i(that)h(are)f(a)n(v)n
(ailable)g(to)g(a)-150 722 y(sentence)f(generation)e(system.)25
b(These)20 b(f)o(actors)g(include:)-150 880 y Fj(Sentence)g(Boundaries)
42 b Fl(\226)20 b(pronouns)d(appear)i(to)h(be)g(the)g(preferred)-67
971 y(referring)k(form)h(for)g(subsequent)g(reference)f(to)j(an)f(item)
g(within)-67 1063 y(the)20 b(same)h(sentence.)-150 1216
y Fj(Distance)f(fr)o(om)g(Last)g(Mention)41 b Fl(\226)21
b(when)g(the)g(last)g(mention)f(of)h(an)-67 1308 y(item)16
b(is)i(se)n(v)o(eral)d(sentences)h(back)g(in)g(the)g(te)o(xt,)h(a)g
(de\002nite)f(descrip-)-67 1399 y(tion)k(is)h(preferred.)-150
1553 y Fj(Discourse)g(Structur)o(e)e(\(as)h(indicated)h(by)f(time)h
(change\))40 b Fl(\226)16 b(if)h(we)-67 1644 y(tak)o(e)25
b(time)f(as)i(a)f(discourse)e(structuring)g(de)n(vice,)i(when)f(the)g
(pre-)-67 1736 y(vious)17 b(reference)g(to)h(an)g(item)g(is)h(at)f(the)
g(same)g(time)g(as)h(the)f(current)-67 1827 y(reference,)i(a)i(pronoun)
d(is)j(preferred.)27 b(A)22 b(de\002nite)g(description)e(is)-67
1918 y(preferred)e(when)i(the)g(time)g(has)h(changed.)-150
2072 y Fj(Ambiguity)41 b Fl(\226)18 b(potential)f(ambiguity)f(must)i
(be)g(tak)o(en)g(into)g(account)-67 2164 y(when)24 b(choosing)f(an)h
(anaphoric)e(e)o(xpression)h(in)i(that)f(a)h(pronoun)-67
2255 y(should)19 b(only)h(be)g(generated)e(if)j(it)g(can)f(be)g(resolv)
o(ed)e(correctly)-5 b(.)-67 2413 y(In)30 b(the)g(ne)o(xt)f(section)h
(we)h(discuss)f(pre)n(vious)f(research)g(on)h(pro-)-150
2504 y(noun)37 b(generation.)78 b(This)39 b(is)h(follo)n(wed)d(by)h(an)
h(introduction)d(of)-150 2595 y(time)31 b(as)g(a)g(structuring)e(de)n
(vice)h(which)g(af)n(fects)g(pronoun)e(genera-)-150 2687
y(tion.)55 b(Ne)o(xt)30 b(we)g(in)m(v)o(estigate)f(ambiguous)f
(anaphoric)g(references.)-150 2778 y(W)-7 b(e)18 b(follo)n(w)e(this)h
(with)g(an)f(algorithm)f(which)h(decides)g(when)h(to)f(use)h(a)-150
2869 y(pronoun)h(v)o(ersus)j(a)g(de\002nite)g(description)e(when)i
(referring)e(to)i(some)-150 2961 y(discourse)30 b(entity)-5
b(.)57 b(After)31 b(this,)j(we)d(report)f(on)h(empirical)f(results)-150
3052 y(of)24 b(the)h(application)d(of)j(our)e(algorithm)g(to)i(a)f
(corpus)g(of)g(Ne)n(w)h(Y)-9 b(ork)-150 3143 y(T)m(imes)20
b(articles.)30 3322 y Fh(Pr)n(e)o(vious)25 b(W)-7 b(ork)24
b(on)h(Pr)n(onoun)h(Generation)-150 3436 y Fl(Fe)n(w)18
b(researchers)f(ha)n(v)o(e)g(gi)n(v)o(en)g(serious)h(consideration)d
(to)j(the)g(prob-)-150 3528 y(lem)29 b(of)g(pronoun)e(generation.)50
b(The)29 b(most)g(common)f(f)o(actor)g(con-)-150 3619
y(sidered)c(has)g(been)g(the)g(accessibility)g(of)g(the)g(referent.)36
b(F)o(or)24 b(e)o(xam-)-150 3710 y(ple,)30 b(a)f(pronoun)d(w)o(ould)i
(be)g(generated)f(if)i(its)g(referent)e(w)o(as)j(suf)n(\002-)-150
3802 y(ciently)24 b(prominent)f(in)i(the)f(preceding)f(te)o(xt.)38
b(Some)25 b(early)f(genera-)-150 3893 y(tion)19 b(w)o(ork)g(\(e.g.,)f
(McDonald)g(\(1980\),)f(McK)n(eo)n(wn)h(\(1985\),)f(McK)n(e-)-150
3984 y(o)n(wn)22 b(\(1983\),)f(Appelt)h(\(1981\)\))e(used)i(a)h(simple)
f(rule)g(to)h(implement)-150 4076 y(this)33 b(idea)e(based)h(on)g
(focus)f(\(Sidner)m(,)g(1979\).)58 b(The)32 b(rule)g(roughly)-150
4167 y(stated)20 b(that)g(if)h(the)f(current)e(sentence)i(is)h(about)e
(the)h(same)g(thing)f(that)-150 4258 y(the)d(pre)n(vious)f(sentence)h
(w)o(as)h(about,)f(use)g(a)h(pronoun)c(to)k(refer)e(to)h(that)-150
4350 y(thing.)27 b(As)22 b(w)o(as)g(pointed)d(out)i(abo)o(v)o(e,)e
(this)j(rule)f(does)f(not)h(pro)o(vide)e(a)-150 4441
y(v)o(ery)e(good)f(match)i(with)g(the)g(referring)e(e)o(xpressions)h
(in)h(our)f(corpus.)-67 4532 y(In)22 b(Dale)h(\(1992\),)d(Dale)j(also)f
(discussed)g(the)g(generation)f(of)h(pro-)-150 4624 y(nouns)g(in)h(the)
g(conte)o(xt)f(of)g(w)o(ork)h(on)f(generating)f(referring)g(e)o(xpres-)
-150 4715 y(sions)e(\(Appelt,)f(1985;)g(Reiter)m(,)h(1990\).)k(He)c
(speci\002ed)g(an)g(algorithm)-150 4806 y(that)34 b(essentially)h
(generated)d(the)j(smallest)g(referring)d(e)o(xpression)-150
4898 y(that)19 b(distinguished)e(the)i(object)f(in)h(question)f(from)g
(all)h(others)g(in)g(the)-150 4989 y(conte)o(xt.)116
4959 y Fe(1)172 4989 y Fl(He)g(generated)e(a)i(pronoun)d(\(or)i
(ellipsis\))h(if)g(one)f(were)g(ad-)-150 5080 y(equate)f(and)g(if)h
(the)g(object)f(being)f(referred)g(to)i(w)o(as)h(the)e(center)g(of)h
(the)-150 5172 y(last)24 b(utterance.)32 b(As)24 b(an)f(e)o(xample)f
(of)g(the)h(kinds)g(of)g(te)o(xts)g(he)g(gener)n(-)-150
5263 y(ated)f(consider:)27 b(\223Soak)21 b(the)h(b)n(utterbeans.)28
b(Drain)21 b(and)g(rinse)h Ff(them)p Fl(.)-6 b(\224)p
-150 5313 499 4 v -45 5369 a Fd(1)-16 5401 y Fi(This)31
b(algorithm)g(w)o(as)h(later)e(re)n(vised)i(in)f(Dale)g(&)g(Reiter)f
(\(1995\))i(to)-150 5475 y(more)21 b(adequately)i(re\003ect)e
(human-generated)i(referring)f(e)o(xpressions)g(and)-150
5550 y(to)d(be)g(more)g(computationally)i(tractable.)2025
83 y Fl(Such)e(an)h(account)f(of)g(pronoun)e(generation,)h(based)h(on)g
(center)g(con-)2025 174 y(stanc)o(y)27 b(appears)f(to)i(w)o(ork)e
(quite)h(well)h(in)g(the)f(domain)f(studied)h(by)2025
266 y(Dale,)e(b)n(ut)e(is)i(unable)d(to)i(account)f(for)g(the)g
(patterns)g(in)h(other)f(kinds)2025 357 y(of)d(naturally)f(occurring)f
(te)o(xt.)2108 475 y(The)k(centering)e(model)i(\(Grosz)f(et)i(al.,)f
(1995\))f(itself)h(mak)o(es)g(pre-)2025 566 y(dictions)15
b(about)g(pronoun)e(generation)g(only)i(in)h(the)g(instances)f(where)
2025 657 y(Rule)22 b(1)g(is)h(applicable.)29 b(Recall)23
b(that)f(centering)e(associates)j(a)f(set)h(of)2025 749
y(forw)o(ard)j(looking)g(centers)h(with)h(each)f(utterance.)46
b(This)28 b(is)g(an)g(or)n(-)2025 840 y(dered)17 b(list)i(of)f(the)h
(discourse)e(entities)i(introduced)c(in)k(the)f(utterance.)2025
931 y(While)k(an)g(acti)n(v)o(e)f(area)h(of)f(research,)g(in)h(English)
f(the)h(order)f(is)h(gen-)2025 1023 y(erally)e(tak)o(en)f(to)i(be)f
(subject,)f(object,)h(other)f(ar)o(guments)f(to)j(the)f(v)o(erb)2025
1114 y(in)28 b(surf)o(ace)g(order)m(,)h(adjuncts)e(of)h(the)g(v)o(erb)f
(in)i(surf)o(ace)f(order)-5 b(.)48 b(The)2025 1205 y(backw)o(ard)17
b(looking)g(center)h(of)g(an)h(utterance)f(is)h(the)g(highest)f(rank)o
(ed)2025 1297 y(element)27 b(of)g(the)h(pre)n(vious)e(utterance')-5
b(s)27 b(forw)o(ard)f(looking)g(centers)2025 1388 y(that)i(is)h
(realized)e(in)h(the)f(current)g(utterance.)46 b(Centering')-5
b(s)27 b(Rule)h(1)2025 1479 y(states)c(that)e(if)h(an)o(y)f(element)g
(of)g(the)g(pre)n(vious)f(utterance')-5 b(s)22 b(forw)o(ard)2025
1570 y(looking)28 b(centers)i(list)h(is)g(realized)e(in)h(the)g
(current)f(utterance)f(as)j(a)2025 1662 y(pronoun,)23
b(then)h(the)g(backw)o(ard)f(looking)g(center)h(must)h(be)f(realized)
2025 1753 y(as)g(a)g(pronoun)c(as)k(well)g(\(Grosz)f(et)h(al.,)f(1995,)
g(p.214\).)32 b(Notice)23 b(that)2025 1844 y(the)e Ff(Mr)-9
b(.)27 b(Curtis)22 b Fl(at)f(the)f(be)o(ginning)e(of)j(the)g(second)e
(sentence)h(in)h(Ex-)2025 1936 y(ample)f(1)h(is)g(an)g(apparent)e
(violation)g(of)i(this)g(rule)f(\(because)g(it)h(is)h(the)2025
2027 y(subject)32 b(of)g(the)g(pre)n(vious)f(sentence)h(b)n(ut)g(is)h
(not)f(pronominalized)2025 2118 y(while)d(another)f(element)g
(mentioned)f(in)i(that)g(sentence)f(is\).)52 b(But,)2025
2210 y(more)23 b(generally)-5 b(,)22 b(we)i(must)f(ha)n(v)o(e)g(a)h
(theory)e(that)h(is)i(able)e(to)h(handle)2025 2301 y(all)d(cases)g(of)f
(pronoun)d(use.)2108 2419 y(A)42 b(pronoun)d(interpretation)h
(algorithm)g(based)i(on)f(centering)2025 2510 y(which)29
b(relied)h(on)f(centering)f(transition)h(preferences)f(w)o(as)j(de)n(v)
o(el-)2025 2601 y(oped)25 b(in)g(Brennan)g(et)h(al.)41
b(\(1987\).)e(Using)26 b(transition)e(preferences)2025
2693 y(in)e(a)h(pronoun)c(generation)h(rule)h(w)o(ould)h(co)o(v)o(er)e
(more)h(cases)i(of)f(pro-)2025 2784 y(noun)29 b(use)i(than)f(is)h(co)o
(v)o(ered)d(by)i(Rule)h(1,)i(b)n(ut)d(the)h(application)e(of)2025
2875 y(such)22 b(transition)g(preferences)e(also)j(pro)o(v)o(ed)d
(unhelpful)h(in)h(e)o(xplain-)2025 2967 y(ing)e(pronoun)d(patterns)j
(in)g(our)g(corpus.)2108 3084 y(Grosz)h(&)h(Sidner)f(\(1986\))e(and)i
(Reichman)f(\(1985\))g(indicate)g(that)2025 3176 y(discourse)e(se)o
(gmentation)e(has)j(an)f(ef)n(fect)g(on)g(the)g(linguistic)g(realiza-)
2025 3267 y(tion)i(of)f(referring)f(e)o(xpressions.)24
b(While)c(this)g(is)h(intuiti)n(v)o(ely)e(appeal-)2025
3358 y(ing,)33 b(it)e(is)h(unclear)d(ho)n(w)h(to)h(apply)f(this)h(to)g
(the)g(generation)d(prob-)2025 3450 y(lem)34 b(\(in)g(part)g(because)g
(it)h(is)g(unclear)e(ho)n(w)h(to)h(de\002ne)e(discourse)2025
3541 y(se)o(gments)i(to)h(a)g(generation)d(system\).)71
b(P)o(assonneau)34 b(\(1996\))g(ar)n(-)2025 3632 y(gues)e(for)f(the)h
(use)g(of)g(the)g(principles)f(of)g(information)f(adequac)o(y)2025
3724 y(and)g(economy)e(in)i(generating)e(anaphoric)g(e)o(xpressions.)53
b(Her)30 b(al-)2025 3815 y(gorithm)g(tak)o(es)i(discourse)e(se)o
(gmentation)f(into)j(account)e(through)2025 3906 y(the)d(use)h(of)f
(focus)f(spaces)i(which)e(are)h(associated)g(with)h(each)e(dis-)2025
3997 y(course)e(se)o(gment.)37 b(Thus,)25 b(P)o(assonneau)f(e)o
(xplains)f(that)i(a)g(fuller)f(de-)2025 4089 y(scription)d(might)h(be)g
(used)g(at)h(a)f(discourse)f(se)o(gment)h(boundary)d(be-)2025
4180 y(cause)e(the)h(set)g(of)f(accessible)h(objects)f(changes)g(at)h
(such)f(boundaries)2025 4271 y(\(though)24 b(she)i(combines)e(this)j
(consideration)d(with)i(centering)e(the-)2025 4363 y(ory)c(which)g(may)
f(o)o(v)o(erride)g(the)h(decisions)g(due)g(to)g(se)o(gment)g(bound-)
2025 4454 y(aries\).)29 b(While)22 b(P)o(assonneau')-5
b(s)20 b(algorithm)g(seems)i(quite)f(appealing,)2025
4545 y(notice)e(that)g(it)i(pro)o(vides)c(no)i(e)o(xplanation)e(of)j
(ho)n(w)e(a)i(discourse)f(se)o(g-)2025 4637 y(ment)25
b(\(boundary\))c(should)j(be)h(de\002ned.)38 b(The)25
b(e)n(v)n(aluation)e(that)i(she)2025 4728 y(pro)o(vided)j(used)j(the)f
(discourse)g(se)o(gments)g(pro)o(vided)e(by)i(a)h(set)h(of)2025
4819 y(nai)n(v)o(e)d(subjects)g(who)g(indicated)g(discourse)f(se)o
(gment)h(boundaries)2025 4911 y(in)c(her)g(te)o(xts.)39
b(W)m(ithout)25 b(such)f(boundaries)f(pro)o(vided,)h(it)h(is)h(impos-)
2025 5002 y(sible)j(to)g(apply)f(her)h(algorithm.)49
b(In)29 b(some)g(sense,)i(the)e(w)o(ork)f(pre-)2025 5093
y(sented)22 b(here)f(is)i(consistent)f(with)g(P)o(assonneau')-5
b(s)21 b(theory)-5 b(.)29 b(What)22 b(we)2025 5185 y(attempt)k(to)g
(add)f(is)i(a)f(de\002nition)f(of)g(discourse)g(se)o(gment)g(which)h
(is)2025 5276 y(well-de\002ned)19 b(and)h(can)g(be)h(deri)n(v)o(ed)e
(from)g(input)h(that)g(an)o(y)g(sentence)2025 5367 y(generator)j(must)h
(ha)n(v)o(e)g(in)h(order)e(to)i(generate)e(a)i(sentence.)37
b(On)25 b(the)2025 5459 y(other)f(hand,)h(we)h(dif)n(fer)e(from)g(P)o
(assonneau)f(in)j(that)f(we)g(do)g(not)f(at-)2025 5550
y(tempt)g(to)g(mak)o(e)g(use)h(of)f(focus)g(spaces)g(in)h(generation.)
35 b(Rather)24 b(we)p eop
%%Page: 3 3
3 2 bop -150 83 a Fl(ar)o(gue)25 b(for)i(e)n(v)n(aluating)e
(informational)f(adequac)o(y)h(on)h(the)h(basis)h(of)-150
174 y(confusable)18 b(objects)i(near)g(the)g(current)f(sentence)h(in)g
(a)h(discourse.)-67 272 y(In)d(the)f(follo)n(wing)g(section)g(we)h
(hypothesize)e(that)i(discourse)f(se)o(g-)-150 363 y(ment)32
b(boundaries)e(\(or)m(,)35 b(perhaps,)e(setting)g(changes\))e(do)h(ha)n
(v)o(e)g(an)-150 454 y(ef)n(fect)g(on)h(appropriate)e(anaphoric)f(e)o
(xpression)i(choice)g(and)g(that)-150 546 y(changes)26
b(in)h(time)g(are)f(mark)o(ers)g(of)h(such)f(boundaries)f(\(in)i(the)f
(sto-)-150 637 y(ries)g(that)f(we)h(ha)n(v)o(e)e(analyzed\).)39
b(W)-7 b(e)26 b(hypothesize)d(that)i(if)h(the)f(cur)n(-)-150
728 y(rent)17 b(and)g(pre)n(vious)f(reference)g(to)h(an)h(entity)f
(occur)f(in)i(clauses)f(refer)n(-)-150 820 y(encing)i(tw)o(o)h(dif)n
(ferent)f(times,)h(a)g(de\002nite)g(description)f(is)i(used)e(\(and)
-150 911 y(when)h(the)g(time)g(referenced)e(is)j(the)g(same,)f(a)g
(pronoun)e(is)j(used\).)221 1105 y Fh(T)-9 b(emporal)25
b(Discourse)g(Structur)n(e)-150 1239 y Fl(In)g(this)h(section,)g(we)f
(describe)g(our)f(approach)f(to)j(using)e(discourse)-150
1331 y(structure)k(for)h(choosing)e(the)i(right)g(referring)e(e)o
(xpression.)50 b(Since)-150 1422 y(we)30 b(are)g(w)o(orking)f(with)h
(stories)h(from)e(ne)n(wspapers)g(we)h(were)g(not)-150
1513 y(able)h(to)h(identify)e(the)h(kind)f(of)h(discourse)g(structure)f
(as)i(assumed)-150 1605 y(by)27 b(Grosz)h(&)g(Sidner)f(\(1986\),)g
(whose)h(dialogues)e(are)i(more)f(task-)-150 1696 y(oriented)38
b(and)g(ha)n(v)o(e)g(clear)h(intentional)f(goals.)81
b(W)-7 b(e)40 b(needed)d(to)-150 1787 y(\002nd)23 b(a)g(structuring)e
(de)n(vice)h(that)h(w)o(as)h(both)e(recognizable)f(and)h(part)-150
1879 y(of)32 b(the)g(input)f(to)h(a)g(sentence)g(generation)e(system.)
60 b(After)32 b(in)m(v)o(es-)-150 1970 y(tigating)k(some)h(w)o(ork)g
(on)g(narrati)n(v)o(e)f(structure)g(\(Genette,)h(1980;)-150
2061 y(Prince,)43 b(1982;)f(V)-11 b(ogt,)43 b(1990\),)k(we)d
(concentrated)d(on)i(temporal)-150 2153 y(structure.)30
b(T)-6 b(emporal)21 b(structure)g(\(an)h(impo)o(v)o(erished)d(notion)i
(of)h(the)-150 2244 y(deictic)c(center)g(\(Nakhimo)o(vsk)o(y)-5
b(,)14 b(1988;)j(W)m(iebe,)h(1994\))e(and)i(related)-150
2335 y(to)28 b(temporal)f(focus)h(\(W)-7 b(ebber)m(,)27
b(1988\)\))f(informally)g(relates)i(to)h(the)-150 2427
y(time)i(being)f(referenced)f(in)i(a)g(te)o(xt.)57 b(This)31
b(structure)f(is)i(often)e(in-)-150 2518 y(dicated)25
b(by)g(linguistic)g(means)g(and)g(must)h(be)f(part)g(of)g(the)h(input)e
(to)-150 2609 y(a)h(sentence)g(generator)-5 b(.)38 b(Changes)25
b(in)g(temporal)e(structure)i(or)f(time)-150 2701 y(may)d(require)f(w)o
(orld)h(kno)n(wledge)e(reasoning)h(to)h(recognize)f(b)n(ut)i(are)-150
2792 y(often)j(indicated)f(by)h(either)g(cue)g(w)o(ords)h(and)f
(phrases)g(\(e.g.,)f Ff(\223nine)-150 2883 y(year)o(s)c(a)o(go\224,)f
(\223a)h(year\224,)g(\223for)g(months\224,)f(\223se)o(ver)o(al)h
(months)f(a)o(go\224)p Fl(\),)-150 2975 y(a)g(change)d(in)j
(grammatical)d(time)j(of)e(the)i(v)o(erb)e(\(e.g.,)g(past)h(tense)g(v)o
(er)n(-)-150 3066 y(sus)27 b(present)f(tense\),)i(or)e(changes)f(in)i
(aspect)f(\(e.g.,)h(atomic)f(v)o(ersus)-150 3157 y(e)o(xtended)c(e)n(v)
o(ents)i(v)o(ersus)g(states)h(as)g(de\002ned)e(by)h(Moens)g(&)g(Steed-)
-150 3248 y(man)c(\(1988\)\).)-67 3346 y(In)e(considering)e(ho)n(w)h
(time)i(change)d(might)i(af)n(fect)f(anaphoric)f(e)o(x-)-150
3437 y(pression)33 b(choice,)k(we)e(consider)e(the)h(choice)g(for)f
(the)h(\002rst)h(men-)-150 3529 y(tion)24 b(of)g(a)h(discourse)e
(entity)h(in)g(a)h(sentence)e(where)h(that)g(entity)g(has)-150
3620 y(recently)31 b(been)g(referred)g(to)h(in)g(the)g(discourse.)60
b(Our)31 b(hypothesis)-150 3711 y(is)j(that:)50 b(Changes)32
b(in)h(time)f(reliably)g(signal)h(discourse)f(se)o(gment)-150
3803 y(boundaries)15 b(in)j(ne)n(wspaper)e(articles;)i(de\002nite)f
(descriptions)g(should)-150 3894 y(appear)24 b(when)g(the)h(current)e
(reference)h(to)h(a)g(discourse)f(entity)h(is)g(in)-150
3985 y(a)h(dif)n(ferent)f(discourse)g(se)o(gment)g(from)g(the)h(last)h
(reference)d(to)i(that)-150 4077 y(entity)20 b(and)f(pronouns)e(should)
i(occur)g(when)h(the)g(pre)n(vious)e(mention)-150 4168
y(is)j(in)f(the)h(same)f(discourse)f(se)o(gment.)-67
4265 y(Notice)e(that)g(our)g(hypothesis)e(does)i Ff(not)g
Fl(co)o(v)o(er)f Ff(long)g(distance)h Fl(sit-)-150 4357
y(uations)g(\226)h(where)g(a)g(discourse)f(entity)h(has)g(not)g(been)f
(referred)f(to)i(for)-150 4448 y(se)n(v)o(eral)27 b(sentences;)k(we)d
(ha)n(v)o(e)f(found)e(that)j(a)g(de\002nite)f(description)-150
4539 y(is)i(almost)f(al)o(w)o(ays)h(used)f(in)g(long)f(distance)h
(situations)g(re)o(gardless)-150 4631 y(of)k(time)g(changes.)59
b(A)32 b(second)f(place)h(where)f(time)i(does)e(not)h(af-)-150
4722 y(fect)25 b(anaphoric)e(e)o(xpression)g(choice)h(is)i(at)f(v)o
(ery)f(short)h(distances)f(\226)-150 4813 y(subsequent)18
b(reference)g(to)h(an)h(object)f Ff(within)h(the)f(same)h(sentence)f
Fl(is)-150 4905 y(almost)h(al)o(w)o(ays)h(realized)f(as)h(a)g(pronoun)d
(re)o(gardless)g(of)i(whether)g(or)-150 4996 y(not)g(the)g(time)g(has)h
(changed.)-67 5093 y(In)32 b(order)f(to)h(e)n(v)n(aluate)f(this)i
(hypothesis,)g(we)g(mapped)e(out)h(the)-150 5185 y(time)25
b(being)g(referenced)e(in)i(our)g(te)o(xts)g(on)g(a)h(clause-by-clause)
d(ba-)-150 5276 y(sis.)29 b(F)o(or)21 b(each)g(clause)g(in)h(the)f(te)o
(xts,)h(we)f(indicated)f(the)i(time)f(which)-150 5367
y(w)o(as)32 b(referred)e(to.)58 b(W)-7 b(e)32 b(distinguished)e
(between)g(e)n(v)o(ents)h(that)g(oc-)-150 5459 y(curred)20
b(at)h(a)g(single)g(instance)g(in)g(time)g(\(atomic)f(e)n(v)o(ents\))g
(and)g(e)n(v)o(ents)-150 5550 y(or)26 b(states)i(that)e(occurred)f(o)o
(v)o(er)g(a)i(span)f(of)g(time)h(\(repeated)e(atomic)2025
83 y(e)n(v)o(ents,)18 b(e)o(xtended)f(e)n(v)o(ents,)h(and)h(states\).)
25 b(F)o(or)18 b(atomic)h(e)n(v)o(ents)f(we)h(al-)2025
174 y(lo)n(wed)k(for)g(both)f(a)i(speci\002c)g(time)g(at)g(which)f(it)h
(occurred)d(and)i(for)g(a)2025 266 y(non-speci\002c)d(time)j(that)f
(indicated)f(the)h(range)f(of)h(uncertainty)-5 b(.)28
b(W)-7 b(e)2025 357 y(allo)n(wed)25 b(time)g(spans)h(to)f(ha)n(v)o(e)g
(both)f(speci\002c)i(end)f(points)g(and)f(un-)2025 448
y(speci\002ed)c(end)g(points)f(as)i(well.)2108 542 y(An)33
b(e)o(xample)e(from)g(our)h(corpus)f(with)i(its)h(associated)e(tempo-)
2025 634 y(ral)20 b(structure)f(may)g(illustrate)h(these)g(labels,)g
(the)g(comple)o(xity)e(of)i(the)2025 725 y(te)o(xts)h(under)e
(consideration,)f(and)h(ho)n(w)h(we)h(propose)e(pronoun)e(gen-)2025
816 y(eration)i(is)i(af)n(fected.)2108 977 y Fg(Example)e(2:)2108
1083 y(\(47a\))42 b Fi(Questioned)24 b(about)f(the)f(criminal)h(acti)n
(vities)f(of)g(the)h(football)2191 1158 y(club,)2108
1252 y Fg(\(47b\))42 b(Mrs.)18 b(Mandela)g Fi(maintained)2108
1346 y Fg(\(47c\))42 b Fi(that)19 b Fg(she)f Fi(had)i(ne)n(v)o(er)g
(had)f(an)o(y)h(control)f(o)o(v)o(er)g(them.)2108 1440
y Fg(\(48a\))42 b Fi(This)21 b(despite)h(testimon)o(y)f(from)g(a)g
(half)g(dozen)i(former)e(mem-)2191 1514 y(bers)2108 1608
y Fg(\(48b\))42 b Fi(that)19 b(the)o(y)h(e)n(v)o(en)g(had)g(to)g(get)g
(permission)g(to)f(go)h(in)g(and)g(out)g(of)2191 1683
y Fg(her)f Fi(yard.)2108 1777 y Fg(\(49a\))42 b(Mrs.)19
b(Mandela)e Fi(also)j(said)2108 1871 y Fg(\(49b\))42
b(she)18 b Fi(had)i(disbanded)g(the)f(club)2108 1965
y Fg(\(49c\))42 b Fi(after)21 b Fg(her)f Fi(husband)j(ask)o(ed)f
Fg(her)f Fi(to,)g(despite)g(e)n(vidence)i(to)e(the)2191
2039 y(contrary)-5 b(.)2108 2133 y Fg(\(50\))42 b(Mrs.)i(Mandela)g
Fi(f)o(aced)i(questions)g(from)f(more)h(than)f(10)2191
2208 y(la)o(wyers)20 b(representing)i(v)n(arious)f(victims)f(and)h(the)
f(panel)h(of)f(com-)2191 2283 y(missioners)f(and)h(their)f(in)m(v)o
(estigators.)2270 3703 y @beginspecial 197 @llx 309 @lly
415 @urx 482 @ury 1842 @rwi @setspecial
%%BeginDocument: time.ps
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def
end
save
-91.0 615.5 translate
1 -1 scale
/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def
$F2psBegin
10 setmiterlimit
n -1000 6100 m -1000 -1000 l 9422 -1000 l 9422 6100 l cp clip
 0.06000 0.06000 sc
% Polyline
7.500 slw
 [15 45] 45 sd
n 5700 3000 m 8400 3000 l gs col-1 s gr  [] 0 sd
% Polyline
 [15 45] 45 sd
n 5700 3300 m 8400 3300 l gs col-1 s gr  [] 0 sd
% Polyline
 [15 45] 45 sd
n 5700 3900 m 8400 3900 l gs col-1 s gr  [] 0 sd
% Polyline
 [15 45] 45 sd
n 5700 4200 m 8400 4200 l gs col-1 s gr  [] 0 sd
% Polyline
 [15 45] 45 sd
n 5700 4500 m 8400 4500 l gs col-1 s gr  [] 0 sd
% Polyline
15.000 slw
n 6000 4500 m 6300 4500 l gs col-1 s gr 
% Polyline
7.500 slw
 [15 60] 60 sd
n 6600 2250 m 6600 4800 l gs col-1 s gr  [] 0 sd
% Polyline
 [15 60] 60 sd
n 7200 2250 m 7200 4800 l gs col-1 s gr  [] 0 sd
% Polyline
15.000 slw
n 7200 4500 m 7500 4500 l gs col-1 s gr 
% Polyline
n 7500 3000 m 7800 3000 l gs col-1 s gr 
% Polyline
7.500 slw
 [15 45] 45 sd
n 5700 2700 m 8400 2700 l gs col-1 s gr  [] 0 sd
% Polyline
15.000 slw
n 6600 4200 m 6900 4200 l gs col-1 s gr 
% Polyline
n 6600 4425 m 6900 4425 l gs col-1 s gr 
% Polyline
7.500 slw
n 6750 4125 m 6750 4500 l gs col-1 s gr 
% Polyline
n 7050 2700 m 7050 3300 l gs col-1 s gr 
% Polyline
n 7650 2700 m 7650 3300 l gs col-1 s gr 
% Polyline
 [15 60] 60 sd
n 8100 2250 m 8100 4800 l gs col-1 s gr  [] 0 sd
% Polyline
15.000 slw
n 8393 4500 m 8408 4500 l gs col-1 s gr
% Polyline
7.500 slw
 [15 60] 60 sd
n 8400 2250 m 8400 4800 l gs col-1 s gr  [] 0 sd
% Polyline
n 8250 4125 m 8250 4500 l gs col-1 s gr 
% Polyline
15.000 slw
n 8100 4425 m 8400 4425 l gs col-1 s gr 
% Polyline
n 8100 4200 m 8400 4200 l gs col-1 s gr 
% Polyline
n 7800 3000 m 8100 3000 l gs col-1 s gr 
% Polyline
7.500 slw
n 7950 2700 m 7950 3300 l gs col-1 s gr 
% Polyline
n 5550 2700 m 5700 2700 l gs col-1 s gr 
% Polyline
n 5550 3000 m 5700 3000 l gs col-1 s gr 
% Polyline
n 5550 3300 m 5700 3300 l gs col-1 s gr 
% Polyline
 [15 45] 45 sd
n 5700 3600 m 8400 3600 l gs col-1 s gr  [] 0 sd
% Polyline
n 5550 3600 m 5700 3600 l gs col-1 s gr 
% Polyline
n 5550 3900 m 5700 3900 l gs col-1 s gr 
% Polyline
n 5550 4200 m 5700 4200 l gs col-1 s gr 
% Polyline
n 5550 4500 m 5700 4500 l gs col-1 s gr 
% Polyline
15.000 slw
n 5700 2250 m 5700 4800 l 8400 4800 l gs col-1 s gr 
% Polyline
n 6900 2775 m 7200 2775 l gs col-1 s gr 
% Polyline
n 6900 3225 m 7200 3225 l gs col-1 s gr 
% Polyline
n 5700 4500 m 6000 4500 l gs col-1 s gr 
% Polyline
7.500 slw
n 6000 4800 m 6000 4875 l gs col-1 s gr 
% Polyline
n 6300 4800 m 6300 4875 l gs col-1 s gr 
% Polyline
n 6600 4800 m 6600 4950 l gs col-1 s gr 
% Polyline
n 6900 4800 m 6900 4875 l gs col-1 s gr 
% Polyline
n 7200 4800 m 7200 4950 l gs col-1 s gr 
% Polyline
n 7500 4800 m 7500 4875 l gs col-1 s gr 
% Polyline
n 8100 4800 m 8100 4875 l gs col-1 s gr 
% Polyline
n 8100 4800 m 8100 4875 l gs col-1 s gr 
% Polyline
n 7800 4800 m 7800 4950 l gs col-1 s gr 
% Polyline
15.000 slw
n 6300 2775 m 6600 2775 l gs col-1 s gr 
% Polyline
n 6300 3225 m 6600 3225 l gs col-1 s gr 
% Polyline
7.500 slw
n 6450 2700 m 6450 3300 l gs col-1 s gr 
% Polyline
n 8400 4800 m 8400 4950 l gs col-1 s gr 
% Polyline
n 5700 4800 m 5700 4950 l gs col-1 s gr 
/Helvetica ff 150.00 scf sf
4800 2775 m
gs 1 -1 sc (1985) col-1 sh gr
/Helvetica ff 150.00 scf sf
4800 3075 m
gs 1 -1 sc (1990) col-1 sh gr
/Helvetica ff 150.00 scf sf
4800 3375 m
gs 1 -1 sc (1991) col-1 sh gr
/Helvetica ff 150.00 scf sf
4800 3675 m
gs 1 -1 sc (1 year) col-1 sh gr
/Helvetica ff 150.00 scf sf
4800 3975 m
gs 1 -1 sc (1 month) col-1 sh gr
/Helvetica ff 150.00 scf sf
4800 4275 m
gs 1 -1 sc (1 week) col-1 sh gr
/Helvetica ff 150.00 scf sf
4800 4575 m
gs 1 -1 sc (now) col-1 sh gr
/Helvetica ff 150.00 scf sf
6825 5100 m
gs 1 -1 sc (48) col-1 sh gr
/Helvetica ff 150.00 scf sf
8175 5100 m
gs 1 -1 sc (50) col-1 sh gr
/Helvetica ff 150.00 scf sf
6075 5100 m
gs 1 -1 sc (47) col-1 sh gr
/Helvetica ff 150.00 scf sf
6075 2475 m
gs 1 -1 sc (N) col-1 sh gr
/Helvetica ff 150.00 scf sf
6375 2475 m
gs 1 -1 sc (P) col-1 sh gr
/Helvetica ff 150.00 scf sf
6975 2475 m
gs 1 -1 sc (P) col-1 sh gr
/Helvetica ff 150.00 scf sf
7275 2475 m
gs 1 -1 sc (N) col-1 sh gr
/Helvetica ff 150.00 scf sf
7575 2475 m
gs 1 -1 sc (P) col-1 sh gr
/Helvetica ff 150.00 scf sf
7875 2475 m
gs 1 -1 sc (PP) col-1 sh gr
/Helvetica ff 150.00 scf sf
8175 2475 m
gs 1 -1 sc (N) col-1 sh gr
/Helvetica ff 120.00 scf sf
5850 4950 m
gs 1 -1 sc (a) col0 sh gr
/Helvetica ff 120.00 scf sf
6450 4950 m
gs 1 -1 sc (c) col0 sh gr
/Helvetica ff 120.00 scf sf
6750 4950 m
gs 1 -1 sc (a) col0 sh gr
/Helvetica ff 120.00 scf sf
7050 4950 m
gs 1 -1 sc (b) col0 sh gr
/Helvetica ff 120.00 scf sf
7650 4950 m
gs 1 -1 sc (b) col0 sh gr
/Helvetica ff 120.00 scf sf
7950 4950 m
gs 1 -1 sc (c) col0 sh gr
/Helvetica ff 150.00 scf sf
7575 5100 m
gs 1 -1 sc (49) col-1 sh gr
/Helvetica ff 120.00 scf sf
6150 4950 m
gs 1 -1 sc (b) col0 sh gr
/Helvetica ff 120.00 scf sf
7350 4950 m
gs 1 -1 sc (a) col0 sh gr
$F2psEnd
rs
showpage
%%EndDocument
 @endspecial 2305 3886 a Fl(Figure)g(1:)26 b(T)-6 b(emporal)18
b(Structure)h(for)h(Example)f(2)2108 4084 y(Figure)25
b(1)g(contains)g(the)h(temporal)e(structure)g(for)h(\(each)g(clause\))
2025 4175 y(of)k(sentences)h(47-50)d(of)j(one)f(of)g(our)g(te)o(xts.)53
b(The)29 b(corresponding)2025 4266 y(sentences)18 b(\(also)g(brok)o(en)
e(into)i(\002nite)g(clauses)h(are)f(contained)e(in)i(Ex-)2025
4358 y(ample)i(2.)2108 4452 y(Notice)i(that)g(sentence)f(47)h(consists)
g(of)g(three)f(clauses.)30 b(The)22 b(\002rst)2025 4543
y(tw)o(o)16 b(\(47a)f(and)g(47b\))f(describe)h(atomic)g(e)n(v)o(ents)g
(that)h(are)f(taking)g(place)2025 4634 y(at)j(the)g(\223no)n(w\224)f
(time)h(of)f(the)h(story)f(\(during)f(the)i(proceedings)d(against)2025
4726 y(Mrs.)30 b(Mandela\).)e(The)22 b(third)f(clause)h(\(47c\))e
(refers)i(to)g(an)f(inde\002nite)2025 4817 y(span)j(of)g(time)h(in)f
(the)g(past)h(\(roughly)d(from)h(1985)g(to)i(1991,)e(during)2025
4908 y(which)i(Mrs.)42 b(Mandela')-5 b(s)25 b(football)g(club)g(e)o
(xisted\).)41 b(Note,)27 b(the)e(use)2025 4999 y(of)20
b(the)g(past)h(perfect)e(indicating)g(the)h(change)f(in)h(time)g(and)g
(setting.)2108 5093 y(As)32 b(Figure)f(1)g(illustrates,)j(there)d(is)h
(a)g(name)f(\(N\))g(reference)e(to)2025 5185 y(Mrs.)c(Mandela)17
b(in)h(\(47b\),)f(and)h(a)g(pronominal)e(\(P\))i(reference)f(to)h(her)
2025 5276 y(in)k(\(47c\).)29 b(This)22 b(pronoun)d(is)k(used)e(e)n(v)o
(en)g(though)f(there)i(is)h(a)f(change)2025 5367 y(in)c(time)g(between)
e(\(47b\))g(and)h(\(47c\))g(and)g(is)h(e)o(xplained)e(because)h(this)
2025 5459 y(is)i(the)g(second)f(reference)e(to)j(Mrs.)25
b(Mandela)17 b(within)i(the)f(same)h(sen-)2025 5550 y(tence)f(\(a)h
(condition)e(that)i(o)o(v)o(errules)d(the)j(time)g(change)e
(hypothesis\).)p eop
%%Page: 4 4
4 3 bop -67 83 a Fl(\(48a\))36 b(represents)h(a)g(change)f(back)h(to)g
(the)h(time)f(of)g(the)h(pro-)-150 174 y(ceedings)15
b(\(note)f(the)i(discourse-deictic)d(reference)h(\(W)-7
b(ebber)m(,)14 b(1991\))-150 266 y(\223This\224\).)45
b(In)26 b(this)i(case,)h(a)e(time)g(span)g(indicates)g(multiple)f
(atomic)-150 357 y(e)n(v)o(ents)g(occurring)e(during)h(that)h(time.)44
b(\(48b\))25 b(again)g(points)h(to)h(the)-150 448 y(time)19
b(span)g(in)g(the)h(past,)f(though)e(this)j(is)g(not)f(e)o(xplicitly)f
(mark)o(ed)g(lin-)-150 540 y(guistically)i(as)i(it)f(w)o(as)h(in)e
(\(47c\).)26 b(Here)20 b(w)o(orld)g(kno)n(wledge)f(must)i(be)-150
631 y(used)k(to)h(understand)d(the)j(time)f(referenced)f(in)h(this)h
(clause.)41 b(Note,)-150 722 y(ho)n(we)n(v)o(er)m(,)24
b(that)i(the)g(time)f(w)o(ould)g(ha)n(v)o(e)g(to)h(be)f(part)h(of)f
(the)h(input)e(to)-150 814 y(a)30 b(generator)m(,)f(and)g(thus)g(our)g
(rules)g(are)g(completely)f(well-de\002ned)-150 905 y(from)19
b(the)h(generation)f(perspecti)n(v)o(e.)-67 1001 y(The)j(use)h(of)g(a)g
(pronoun)d(to)j(refer)e(to)i(Mrs.)33 b(Mandela)22 b(in)h(\(48b\))e(is)
-150 1092 y(w)o(arranted)27 b(by)g(our)h(hypothesis,)g(because)f(the)h
(clause)g(containing)-150 1183 y(the)22 b(pre)n(vious)f(mention)g(of)h
(Mrs.)32 b(Mandela,)22 b(\(47c\),)g(references)f(the)-150
1275 y(same)f(time)h(as)g(is)g(referenced)d(in)i(\(48b\).)-67
1371 y(Because)28 b(there)f(is)h(a)g(time)g(change)e(between)g(\(48b\))
g(and)h(\(49a\),)-150 1462 y(our)i(hypothesis)f(e)o(xplains)h(the)g
(appearance)f(of)h(the)h(proper)e(name)-150 1553 y(in)23
b(\(49a\))e(e)n(v)o(en)g(though)g(it)i(occurs)f(just)h(after)f(a)h
(pronoun)c(\(in)k(\(48b\)\))-150 1645 y(co-specifying)d(with)j(the)g
(same)f(character)-5 b(.)1136 1615 y Fe(2)1201 1645 y
Fl(The)23 b(pronouns)d(in)j(the)-150 1736 y(remainder)d(of)j(\(49\))e
(are)h(e)o(xplained)e(because)i(the)o(y)g(are)g(subsequent)-150
1827 y(references)16 b(within)h(the)g(same)g(sentence)g(\(despite)f
(the)i(f)o(act)f(that)g(the)o(y)-150 1919 y(refer)g(to)g(an)g
(unspeci\002ed)f(time)i(in)f(the)g(past)h(which)f(is)h(dif)n(ferent)e
(from)-150 2010 y(the)27 b(time)g(referenced)e(in)i(\(49a\)\).)44
b(Finally)-5 b(,)28 b(the)f(use)h(of)e(a)i(name)e(in)-150
2101 y(\(50\))f(is)h(again)f(indicated)g(by)g(the)h(change)f(in)h(time)
g(between)f(\(49c\))-150 2193 y(and)20 b(\(50\).)605
2383 y Fh(Ambiguities)-150 2513 y Fl(Of)39 b(course,)k(the)38
b(choice)g(of)h(referring)e(e)o(xpression)g(is)j(not)e(only)-150
2604 y(guided)15 b(by)g(discourse)g(structure;)i(there)e(is)i(also)f
(an)g(in\003uence)f(due)g(to)-150 2695 y(ambiguities.)38
b(Dale)25 b(\(1992\))d(generated)h(referring)g(e)o(xpressions)g(so)-150
2787 y(that)17 b(the)o(y)e(could)h(be)g(distinguished)f(from)h(the)g
(other)g(discourse)g(enti-)-150 2878 y(ties)i(mentioned)d(in)j(the)f
(conte)o(xt.)23 b(This)17 b(strate)o(gy)f(can)h(be)g(interpreted)-150
2969 y(as:)30 b(Generate)21 b(a)i(pronoun)c(whene)n(v)o(er)h(it)j(is)g
(not)f(ambiguous.)29 b(Ho)n(w-)-150 3061 y(e)n(v)o(er)m(,)h(ho)n(w)e
(one)h(should)f(de\002ne)g(conte)o(xt)g(is)i(not)f(quite)f(clear)-5
b(.)52 b(F)o(or)-150 3152 y(this)22 b(de\002nition)e(we)h(choose)f(a)i
(span)f(of)g(te)o(xt)g(considered)e(important)-150 3243
y(in)24 b(our)g(pre)n(vious)e(w)o(ork)h(on)h(anaphora)e(resolution)h
(\(Strube,)g(1998\),)-150 3335 y(and)k(de\002ne)g(a)g(referring)f(e)o
(xpression)f(as)j(ambiguous)d(if)j(there)f(is)h(a)-150
3426 y(competing)19 b(antecedent)h(\(i.e.)g(another)g(discourse)g
(entity)h(matching)-150 3517 y(in)e(number)f(and)g(gender\))g
(mentioned)f(in)i(the)h(pre)n(vious)d(sentence)i(or)-150
3609 y(to)h(the)g(left)f(of)h(that)g(referring)d(e)o(xpression)h(in)i
(the)g(current)e(sentence.)-150 3700 y(Of)i(the)h(437)e(referring)f(e)o
(xpression)h(in)h(the)h(te)o(xts)f(we)h(analyzed,)d(104)-150
3791 y(were)k(considered)f(ambiguous)f(by)i(this)g(de\002nition.)31
b(Of)22 b(these)g(only)-150 3883 y(51)g(were)g(realized)g(as)h(a)g
(de\002nite)f(description.)29 b(Thus)22 b(a)h(rule)f(which)-150
3974 y(says)j(to)f(use)h(a)g(de\002nite)e(description)g(if)i(a)g
(pronoun)c(w)o(ould)j(be)g(am-)-150 4065 y(biguous)j(according)f(to)j
(the)f(de\002nition)g(appears)f(to)i(be)f(too)g(strict.)-150
4157 y(Therefore)21 b(we)j(need)f(to)h(consider)f(ambiguous)e(cases)j
(in)g(more)f(de-)-150 4248 y(tail.)-67 4344 y(T)-7 b(o)24
b(handle)f(these)h(cases)g(we)g(turned)f(to)h(pronoun)d(resolution)h
(al-)-150 4435 y(gorithms.)59 b(Our)32 b(intuition)f(w)o(as)i(that)f(a)
g(pronoun)d(could)j(be)f(gen-)-150 4527 y(erated)f(to)h(refer)f(to)h(a)
h(particular)d(discourse)h(entity)h(if)g(a)g(pronoun)-150
4618 y(resolution)f(algorithm)g(w)o(ould)g(choose)h(that)g(entity)g(as)
h(a)g(referent)-150 4709 y(for)25 b(the)g(pronoun.)37
b(T)-7 b(o)25 b(our)f(kno)n(wledge,)g(there)h(are)g(only)f(tw)o(o)i
(pro-)-150 4800 y(noun)h(resolution)h(algorithms)g(that)h(are)f
(speci\002ed)h(in)g(enough)e(de-)-150 4892 y(tail)21
b(to)f(w)o(ork)f(on)g(unrestricted)g(naturally)f(occurring)g(te)o(xt:)
25 b(Brennan)-150 4983 y(et)30 b(al.)55 b(\(1987\))27
b(using)j(the)g(de\002nition)e(of)i(utterance)f(according)e(to)-150
5074 y(Kame)o(yama)g(\(1998\),)h(and)g(Strube)g(\(1998\).)48
b(Strube)28 b(\(1998\))e(e)n(v)n(al-)p -150 5164 499
4 v -45 5219 a Fd(2)-16 5251 y Fi(Note)16 b(that)g(the)g(use)g(of)g
(this)g(de\002nite)g(description)h(cannot)f(be)h(e)o(xplained)-150
5326 y(by)22 b(a)f(topic)g(shift)g(since)g(there)g(is)g(no)h(topic)f
(shift)g(in)g(between)g(the)h(pre)n(vious)-150 5401 y(te)o(xt)f(and)h
(\(49\).)31 b(At)21 b(least)h(tw)o(o)f(discourse)i(entities)e(\()p
Fc(\223Mr)o(s.)g(Mandela\224)h Fi(and)-150 5475 y(the)15
b Fc(\223football)h(club\224)p Fi(\))f(are)g(constant,)i(only)e(Mrs.)h
(Mandela')l(s)g(husband)h(does)-150 5550 y(not)i(occur)h(in)f(the)g
(immediately)g(preceding)h(sentences.)2025 83 y Fl(uated)30
b(the)g(ef)n(fecti)n(v)o(eness)f(of)h(these)h(tw)o(o)g(algorithms)e(on)
h(the)g(task)2025 174 y(of)23 b(pronoun)d(resolution)h(in)i(some)g
(naturally)e(occurring)g(te)o(xts.)33 b(Be-)2025 266
y(cause)26 b(Strube')-5 b(s)25 b(algorithm)f(sho)n(wed)h
(signi\002cantly)f(better)h(results,)2025 357 y(we)c(ha)n(v)o(e)e
(turned)g(to)h(it)h(for)f(guidance)e(in)j(pronoun)c(generation.)2108
452 y(The)j(idea)h(is)g(that)g(if)g(we)g(w)o(ant)g(to)f(refer)g(to)h(a)
g(discourse)f(entity)-5 b(,)19 b Fb(E)p Fl(,)2025 543
y(b)n(ut)28 b(there)f(is)i(a)f(competing)d(antecedent,)j
Fb(C)p Fl(,)g(we)g(look)f(to)h(Strube')-5 b(s)2025 634
y(algorithm)22 b(in)i(the)f(follo)n(wing)f(w)o(ay)-5
b(.)35 b(If)24 b(Strube')-5 b(s)23 b(algorithm)f(w)o(ould)2025
726 y(resolv)o(e)31 b(a)h(pronoun)d(to)j(be)f Fb(E)p
Fl(,)h(we)g(use)g(a)g(pronoun.)57 b(If,)34 b(instead,)2025
817 y(Strube')-5 b(s)23 b(algorithm)f(w)o(ould)g(prefer)g
Fb(C)i Fl(as)f(the)h(referent)e(of)g(the)i(pro-)2025
908 y(noun,)19 b(we)h(use)h(a)f(de\002nite)g(description)f(to)h(refer)f
(to)i Fb(E)p Fl(.)2108 1003 y(Our)36 b(analysis)g(sho)n(wed)f(that)h
(the)g(use)h(of)e(Strube')-5 b(s)36 b(algorithm)2025
1094 y(sho)n(wed)15 b(impro)o(v)o(ement,)e(b)n(ut)i(it)h(seemed)f(to)h
(be)f(too)g(liberal)g(with)h(sug-)2025 1186 y(gesting)23
b(pronouns)f(when)h(the)h(competing)e(antecedent)g(w)o(as)j(in)f(the)
2025 1277 y(pre)n(vious)c(sentence.)27 b(Thus,)21 b(the)h(rule)f(that)g
(we)h(settled)f(on)g(is)h(sho)n(wn)2025 1368 y(in)e(Figure)g(2.)2187
1544 y Fi(1.)41 b Fc(If)21 b Fi(this)g(is)g(the)g(\002rst)f(occurrence)
j(of)e(X)g(in)g(the)g(current)g(sen-)2284 1618 y(tence)f(and)2243
1743 y(\(a\))41 b Fc(if)22 b Fi(there)g(is)g(a)g(competing)i
(antecedent)f(in)f(the)g Fc(pr)m(e)o(vious)2367 1818
y Fi(sentence,)e(use)f(a)g(de\002nite)g(description;)2239
1909 y(\(b\))41 b Fc(if)17 b Fi(there)g(is)g(a)g(competing)h
(antecedent)g(in)f(the)g Fc(same)g Fi(sen-)2367 1984
y(tence)j(\(i.e.,)d(to)i(the)g(left\))f(and)2328 2075
y(i.)41 b Fc(if)18 b Fi(Strube')l(s)g(algorithm)h(w)o(ould)g(resolv)o
(e)g(a)f(pronoun)j(in)2409 2150 y(this)e(position)g(to)g(be)g(X,)f(use)
i(a)f(pronoun;)2307 2233 y(ii.)41 b Fc(else)19 b Fi(use)g(a)g
(de\002nite)g(description;)2187 2374 y(2.)41 b Fc(if)20
b Fi(this)g(is)g(a)g(subsequent)i(occurrence)g(of)f(X)f(in)g(the)g
(current)2284 2449 y(sentence)g(and)2243 2573 y(\(a\))41
b Fc(if)31 b Fi(there)f(is)h(an)g(interv)o(ening)h(competing)g
(antecedent,)2367 2648 y(use)20 b(a)f(de\002nite)f(description;)2239
2739 y(\(b\))41 b Fc(if)30 b Fi(there)g(is)g(no)g(interv)o(ening)h
(competing)h(antecedent,)2367 2814 y(use)20 b(a)f(pronoun.)2025
2978 y Fl(Figure)30 b(2:)47 b(Realization)31 b(of)g(the)g(Referring)e
(Expression)h(X)h(when)2025 3078 y(Competing)19 b(Antecedents)g(Exist)
2077 3368 y Fh(Anaphoric)26 b(Expr)n(ession)f(Generation)h(Algorithm)
2025 3494 y Fl(In)e(the)f(pre)n(vious)g(sections)g(we)i(ha)n(v)o(e)e
(ar)o(gued)f(that)h(temporal)g(struc-)2025 3586 y(ture)37
b(should)g(in\003uence)g(pronoun)e(choice)i(and)g(that)h(ambiguous)2025
3677 y(cases)29 b(need)f(to)g(be)g(handled)f(separately)-5
b(.)48 b(In)28 b(addition,)h(we)f(found)2025 3768 y(that)19
b(if)h(the)f(distance)g(between)g(the)g(current)f(reference)g(and)h
(the)g(pre-)2025 3860 y(vious)28 b(mention)f(of)h(the)g(discourse)f
(entity)h(being)g(referred)e(to)j(w)o(as)2025 3951 y(f)o(ar)19
b(\(o)o(v)o(er)f(tw)o(o)h(sentences\),)g(a)g(de\002nite)g(description)f
(w)o(as)i(almost)f(al-)2025 4042 y(w)o(ays)e(used.)23
b(Finally)-5 b(,)17 b(we)f(found)f(that)i(when)f(an)g(entity)g(w)o(as)h
(referred)2025 4134 y(to)26 b(multiple)e(times)i(in)g(a)g(sentence,)g
(a)g(pronoun)d(w)o(as)j(usually)f(used)2025 4225 y(for)20
b(subsequent)e(references)h(in)h(a)h(sentence.)2108 4320
y(Based)k(on)f(these)g(\002ndings,)g(we)h(propose)d(the)j(algorithm)d
(for)i(re-)2025 4411 y(alizing)c(anaphoric)e(e)o(xpressions)h(sho)n(wn)
g(in)i(Figure)e(3.)2710 4599 y Fh(Empirical)25 b(Data)2025
4725 y Fl(W)-7 b(e)31 b(applied)e(the)h(algorithm)f(described)f(in)i
(the)g(pre)n(vious)f(section)2025 4816 y(to)c(three)f(te)o(xts)h(from)f
(the)g Ff(Ne)o(w)i(Y)-8 b(ork)25 b(T)-5 b(imes)p Fl(.)40
b(Articles)25 b(were)g(rang-)2025 4907 y(ing)k(from)g(a)h(frontpage)d
(article)j(to)f(local)h(ne)n(ws.)53 b(W)-7 b(e)31 b(applied)e(the)2025
4999 y(algorithm)23 b(to)i(all)g(references)f(to)h(persons)f(in)g
(these)h(te)o(xts.)39 b(The)24 b(al-)2025 5090 y(gorithm)h(w)o(as)i
(correct)e(in)h(370)g(cases)g(\(84.7\045\),)g(and)g(wrong)f(in)h(67)
2025 5181 y(cases)d(\(15.3\045\).)28 b(In)21 b(Figure)h(4)g(we)g(sho)n
(w)g(the)f(distrib)n(ution)g(o)o(v)o(er)g(the)2025 5273
y(rules)f(speci\002ed)g(in)g(the)h(algorithm.)2108 5367
y(In)k(order)f(to)i(interpret)e(the)i(results)f(of)g(the)h(algorithm,)f
(we)h(must)2025 5459 y(ha)n(v)o(e)c(some)g(comparison.)30
b(W)-7 b(e)24 b(use)f(the)f(simple)h(scheme)f(sho)n(wn)f(in)2025
5550 y(Figure)f(5)g(for)f(comparison)f(purposes.)p eop
%%Page: 5 5
5 4 bop 12 51 a Fi(1.)41 b Fc(If)23 b Fi(this)f(is)h(a)f
Fg(long)h(distance)f(anaphoric)h(r)o(efer)o(ence)f Fi(\(i.e.,)109
126 y(if)16 b(the)f(pre)n(vious)i(reference)g(to)e(X)h(w)o(as)g(more)g
(than)g(tw)o(o)f(sen-)109 201 y(tences)20 b(prior\))f(use)g(a)g
Fg(de\002nite)e(description)p Fi(;)12 342 y(2.)41 b Fc(else)109
417 y(if)f Fi(this)h(is)f(an)h Fg(unambiguous)e(r)o(efer)o(ence)i
Fi(\(i.e.,)k(there)109 491 y(is)34 b(no)g(competing)h(antecedent\))f
(and)h(this)e(is)g(an)h Fg(intra-)109 566 y(sentential)19
b(anaphor)g Fi(\(i.e.,)f(this)h(is)g(not)g(the)h(\002rst)e(mention)109
641 y(of)h(X)g(in)g(the)g(current)g(sentence\))h(use)f(a)g
Fg(pr)o(onoun)p Fi(;)12 782 y(3.)41 b Fc(else)109 857
y(if)19 b Fi(this)g(is)g(a)g Fg(time)g(change)g Fi(\(i.e.,)f(there)i
(is)e(a)i(dif)n(ference)g(be-)109 932 y(tween)h(the)g(time)f(of)h(the)g
(clause)g(with)f(the)h(pre)n(vious)h(refer)o(-)109 1006
y(ence)27 b(to)e(X)h(and)g(the)g(time)f(of)h(the)g(current)g(clause\))g
(use)g(a)109 1081 y Fg(de\002nite)18 b(description)p
Fi(;)12 1222 y(4.)41 b Fc(else)109 1297 y(if)20 b Fi(there)h(is)f(a)g
Fg(competing)g(antecedent)g Fi(\(i.e.,)f(another)i(ob-)109
1372 y(ject)h(in)f(the)g(pre)n(vious)i(or)f(current)f(sentence)i(that)e
(matches)109 1446 y(the)c(type)g(and)g(number)g(of)g(X\))f(use)g(the)h
Fg(rule)f(f)n(ound)f(in)g(Fig-)109 1521 y(ur)o(e)k(2)p
Fi(;)12 1662 y(5.)41 b Fc(else)109 1737 y Fi(for)19 b(the)g
Fg(r)o(emaining)f(cases)i Fi(use)f(a)g Fg(pr)o(onoun)p
Fi(.)-150 1900 y Fl(Figure)e(3:)24 b(Algorithm)17 b(for)g(Generating)f
(the)i(Appropriate)e(F)o(orm)h(for)-150 2000 y(a)k(Referring)e
(Expression)f(X)-52 2181 y Fg(Rule)h(Name)p 1055 2203
4 75 v 803 w Fi(number)101 b(percentage)p -101 2206 1910
4 v -52 2259 a Fg(All)19 b(Rules)557 b Fi(correct)p 1055
2281 4 75 v 217 w(370)231 b(84.7\045)816 2333 y(wrong)p
1055 2356 V 254 w(67)g(15.3\045)p -101 2359 1910 4 v
-52 2411 a Fg(Long)19 b(Distance)g(Anaph.)137 b Fi(correct)p
1055 2434 4 75 v 254 w(46)231 b(97.9\045)816 2486 y(wrong)p
1055 2509 V 291 w(1)268 b(2.1\045)p -101 2512 1910 4
v -52 2564 a Fg(Intra-sentential)18 b(Anaph.)98 b Fi(correct)p
1055 2587 4 75 v 217 w(168)287 b(96\045)816 2639 y(wrong)p
1055 2661 V 291 w(7)324 b(4\045)p -101 2665 1910 4 v
-52 2717 a Fg(T)o(ime)19 b(Rules)f Fi(\(3)h(&)g(5\))250
b(correct)p 1055 2739 4 75 v 217 w(116)231 b(72.5\045)816
2792 y(wrong)p 1055 2814 V 254 w(44)g(27.5\045)p -101
2817 1910 4 v -52 2870 a Fg(Competing)19 b(Antecedent)117
b Fi(correct)p 1055 2892 4 75 v 254 w(40)231 b(72.7\045)816
2944 y(wrong)p 1055 2967 V 254 w(15)g(27.2\045)287 3115
y Fl(Figure)19 b(4:)26 b(Results)21 b(of)f(the)g(Algorithm)-67
3393 y(The)25 b(results)h(of)f(applying)f(these)i(rules)f(gi)n(v)o(e)g
(343)f(correct)h(cases)-150 3484 y(\(78.5\045\))18 b(and)i(94)f
(incorrect)g(ones)g(\(21.5\045\).)k(Hence)d(our)f(algorithm)-150
3575 y(reduces)g(the)i(error)e(rate)h(by)g(28.9\045.)491
3768 y Fh(Related)26 b(Resear)n(ch)-150 3901 y Fl(A)h(signi\002cant)f
(amount)g(of)g(w)o(ork)g(in)h(linguistics)g(has)g(in)m(v)o(estigated)
-150 3992 y(the)e(use)h(of)f(dif)n(ferent)f(kinds)g(of)h(anaphoric)f
(referring)f(e)o(xpressions)-150 4083 y(in)f(discourse)f(and)g(their)g
(relationship)g(to)g(ease)i(of)e(comprehension.)-150
4175 y(See)27 b(Arnold)f(\(1998\))e(for)i(a)h(discussion)f(of)h(se)n(v)
o(eral)f(of)g(the)h(f)o(actors)-150 4266 y(in)m(v)n(olv)o(ed)h(in)h
(referring)f(e)o(xpression)g(choice.)52 b(In)30 b(man)o(y)e(cases)j
(the)-150 4357 y(v)n(arious)c(f)o(actors)h(seem)h(to)f(af)n(fect)g(the)
g Ff(accessibility)g Fl(of)g(a)h(referent)-150 4449 y(\(where)16
b(accessibility)i(is)g(intended)e(in)h(a)h(broad)e(sense)h(to)h(co)o(v)
o(er)d(both)-150 4540 y(\223topic)29 b(accessibility\224)h(\(Gi)n(v)n
(on,)f(1983\))f(and)i(accessibility)g(due)f(to)-150 4631
y(f)o(actors)24 b(such)f(as)i(recenc)o(y)d(of)i(mention\).)35
b(Basically)-5 b(,)25 b(the)e(more)h(ac-)-150 4723 y(cessible)17
b(a)h(referent)e(the)h(more)f(underspeci\002ed)e(a)k(referring)d(e)o
(xpres-)-150 4814 y(sion)29 b(should)e(be.)50 b(Accessibility)29
b(e)o(xplains)e(the)i(apparent)e(\223name-)-150 4905
y(name)i(penalty\224)f(as)i(e)o(xamined)d(in)j(Gordon)e(&)h(Hendrick)f
(\(1998\),)-150 4997 y(for)20 b(e)o(xample.)-67 5093
y(Our)i(w)o(ork)g(ar)o(gues)f(that)i(f)o(actors)f(be)o(yond)e
(accessibility)j(must)g(be)-150 5185 y(considered)29
b(in)i(anaphoric)d(e)o(xpression)h(choice.)55 b(It)31
b(is)h(consistent)-150 5276 y(with)23 b(w)o(ork)f(such)g(as)h(V)-11
b(onk)22 b(et)i(al.)32 b(\(1992\))21 b(whose)h(e)o(xperiments)f(in-)
-150 5367 y(dicate)31 b(that)h(a)g(referring)e(e)o(xpression)g(\223...)
59 b(that)32 b(is)h(more)d(speci\002c)-150 5459 y(than)23
b(is)i(necessary)d(for)h(the)h(reco)o(v)o(ery)d(of)i(the)h(intended)e
(referent)g(...)-150 5550 y(marks)17 b(the)g(be)o(ginning)e(of)i(a)h
(ne)n(w)f(theme)g(concerning)e(the)i(same)g(dis-)2196
51 y Fi(1.)42 b Fc(If)22 b Fi(this)h(is)f(a)h Fg(long)f(distance)g
(anaphoric)h(r)o(efer)o(ence)f Fi(\(i.e.,)2294 126 y(if)h(the)i(pre)n
(vious)g(reference)g(to)f(this)g(item)f(is)h(greater)h(than)2294
201 y(tw)o(o)19 b(sentences)h(prior\))f(use)g(a)g Fg(de\002nite)e
(description)p Fi(;)2196 342 y(2.)42 b Fc(else)2294 417
y(if)19 b Fi(there)i(is)f(a)g Fg(competing)g(antecedent)g
Fi(\(i.e.,)f(another)j(ob-)2294 491 y(ject)17 b(in)h(the)g(pre)n(vious)
h(or)f(current)g(sentences)h(that)e(matches)2294 566
y(the)i(pronoun)j(which)e(w)o(ould)g(be)g(used)g(to)g(refer)f(to)h
(this)f(en-)2294 641 y(tity\))f(use)h(a)g Fg(de\002nite)e(description)p
Fi(;)2196 782 y(3.)42 b Fc(else)2294 857 y Fi(the)19
b(anaphoric)h(e)o(xpression)g(w)o(ould)f(be)g Fg(unambiguous)f
Fi(so)2294 932 y(use)h(a)g Fg(pr)o(onoun)p Fi(.)2573
1095 y Fl(Figure)g(5:)25 b(Simple)20 b(Algorithm)2025
1373 y(course)25 b(referent.)-6 b(\224)39 b(\(V)-11 b(onk)25
b(et)h(al.,)f(1992,)g(page)g(304\).)40 b(The)o(y)24 b(ar)o(gue)2025
1464 y(that)32 b(such)f(o)o(v)o(erspeci\002ed)f(e)o(xpressions)g(are)i
(serving)e(a)i(discourse)2025 1555 y(function)d(of)i(indicating)f
(boundaries.)56 b(This)31 b(w)o(ork)f(does)h(not)g(de-)2025
1647 y(\002ne)26 b(what)g(a)h(discourse)e(se)o(gment)h(boundary)d
(actually)i(is.)44 b(On)27 b(the)2025 1738 y(other)19
b(hand,)f(using)h(the)h(de\002nition)e(of)h(time)h(change)e(as)i(a)g
(boundary)2025 1829 y(condition,)28 b(our)f(w)o(ork)g(is)i(consistent)f
(with)g(their)g(hypothesis.)46 b(In-)2025 1921 y(terestingly)-5
b(,)19 b(V)-11 b(onk)19 b(et)i(al.)k(\(1992\))18 b(found)h(that)h(in)h
(discourses)e(where)2025 2012 y(a)25 b(theme)f(change)f(w)o(as)i(well)g
(mark)o(ed)f(by)g(other)f(means)i(\(e.g.,)f(by)g(a)2025
2103 y(preposed)e(adv)o(erbial)f(phrase)i(or)g(a)h(subordinate)d
(clause)j(indicating)2025 2195 y(time)f(or)g(place\))f(that)h(pronouns)
e(were)h(much)g(more)h(common)e(e)n(v)o(en)2025 2286
y(though)29 b(a)i(ne)n(w)f(theme)g(w)o(as)h(be)o(gun.)55
b(Presumably)29 b(such)h(phrases)2025 2377 y(mark)c(the)g(theme)g
(change)f(well,)j(and)e(thus)g(it)h(is)h(not)e(necessary)f(to)2025
2469 y(also)17 b(mark)f(the)h(change)f(via)h(an)g(o)o(v)o
(erspeci\002ed)d(description.)23 b(W)-7 b(e)18 b(are)2025
2560 y(currently)e(reanalyzing)g(our)h(data)h(in)g(light)g(of)f(that)h
(\002nding)f(to)h(see)h(of)2025 2651 y(it)i(pro)o(vides)d(a)j(fuller)f
(account)e(of)i(the)h(naturally)e(occurring)e(data.)2108
2748 y(Approaches)22 b(which)g(de\002ne)h(discourse)g(se)o(gments)g(on)
g(the)g(basis)2025 2839 y(of)i(reference)f(resolution)g(\(Sidner)m(,)g
(1979;)g(Suri)i(&)f(McCo)o(y)-5 b(,)25 b(1994;)2025 2931
y(Strube)32 b(&)g(Hahn,)g(1997\))f(are)h(not)g(useful)g(for)g(our)g
(purposes)f(be-)2025 3022 y(cause)22 b(the)o(y)g(require)f(referring)g
(e)o(xpressions)g(for)h(recognizing)e(se)o(g-)2025 3113
y(ment)k(boundaries.)35 b(In)24 b(contrast)g(to)g(these)g(approaches,)f
(we)i(de\002ne)2025 3205 y(se)o(gment)c(boundaries)f(independently)f
(from)i(reference)f(resolution)2025 3296 y(so)25 b(that)h(in)f(this)g
(respect)g(our)f(w)o(ork)h(is)h(in)f(line)g(with)g(Grosz)g(&)h(Sid-)
2025 3387 y(ner')-5 b(s)20 b(\(1986\))e(de\002nitions.)2662
3580 y Fh(Futur)n(e)26 b(Dir)n(ections)2025 3712 y Fl(In)18
b(analyzing)e(our)h(data,)i(there)e(are)h(se)n(v)o(eral)f(places)i(for)
e(further)f(con-)2025 3804 y(sideration.)55 b(One)31
b(problem)e(is)j(that)e(our)g(rule)h(which)f(indicates)g(a)2025
3895 y(de\002nite)19 b(description)f(should)g(be)i(used)f(in)g(a)h
(time)g(change)e(o)o(v)o(er)o(gen-)2025 3986 y(erates)k(de\002nite)e
(descriptions.)28 b(F)o(ollo)n(wing)20 b(V)-11 b(onk)20
b(et)i(al.)29 b(\(1992\))19 b(we)2025 4078 y(plan)30
b(to)h(in)m(v)o(estigate)e(whether)g(de\002nite)h(descriptions)f(might)
h(best)2025 4169 y(be)18 b(vie)n(wed)f(as)i(boundary)c(mark)o(ers)i
(and)g(whether)g(other)g(mark)o(ers)g(of)2025 4260 y(discourse)30
b(boundaries)f(\(e.g.,)k(preposed)d(adv)o(erbial)f(phrases\))i(are)2025
4352 y(found)25 b(in)j(places)f(where)g(our)f(algorithm)g(suggests)h(a)
g(de\002nite)g(de-)2025 4443 y(scription)c(because)h(of)g(a)g(time)g
(change)f(b)n(ut)h(a)h(pronoun)c(appears)i(in)2025 4534
y(the)d(te)o(xt.)2108 4631 y(In)28 b(places)h(where)f(our)f(algorithm)g
(o)o(v)o(er)o(generates)e(pronouns,)j(a)2025 4723 y(more)h
(sophisticated)g(time)h(analysis)g(may)f(be)h(helpful.)53
b(Our)29 b(cur)n(-)2025 4814 y(rent)23 b(analysis)g(distinguishes)f
(between)g(four)g(types)h(of)g(time)g(and)g(is)2025 4905
y(dri)n(v)o(en)e(by)h(both)f(semantic)h(cues)h(in)f(the)h(te)o(xt)f
(\(e.g.,)g(adv)o(erbial)e(time)2025 4997 y(phrases\))c(and)g(changes)f
(in)i(tense.)24 b(Nakhimo)o(vsk)o(y)13 b(\(1988\))h(also)j(uses)2025
5088 y(changes)k(in)i(\223time)f(scale\224)g(as)h(a)g(mark)o(er)e(for)h
(changes)f(in)h(time.)31 b(W)-7 b(e)2025 5179 y(plan)21
b(to)h(in)m(v)o(estigate)d(this)j(to)g(see)g(whether)e(it)i(e)o
(xplains)f(more)f(of)i(the)2025 5271 y(e)o(xamples.)36
b(Nakhimo)o(vsk)o(y)21 b(\(1988\))h(also)j(describes)f(se)n(v)o(eral)f
(other)2025 5362 y(mark)o(ers)j(for)f(a)i(setting)g(change,)f(and)g
(these)g(will)h(also)g(be)g(in)m(v)o(esti-)2025 5453
y(gated)19 b(to)i(see)f(if)h(the)o(y)e(are)h(indicati)n(v)o(e)f(of)h
(de\002nite)g(description)f(use.)2108 5550 y(Another)24
b(line)g(of)h(future)f(research)g(in)m(v)n(olv)o(es)f(further)h(in)m(v)
o(estiga-)p eop
%%Page: 6 6
6 5 bop -150 83 a Fl(tion)21 b(of)g(the)h(ambiguous)d(cases.)30
b(Our)21 b(current)f(rule)h(w)o(as)h(de)n(v)o(eloped)-150
174 y(by)k(e)n(v)n(aluating)f(se)n(v)o(eral)h(dif)n(ferent)f
(possibilities)i(\(e.g.,)g(using)f(time)-150 266 y(change)15
b(rules,)h(dif)n(ferent)e(pronoun)f(resolution)i(algorithms\))f(and)h
(se-)-150 357 y(lecting)h(a)g(rule)g(that)g(e)o(xplains)f(most)h(of)f
(the)h(cases.)25 b(Still,)17 b(the)f(number)-150 448
y(of)25 b(ambiguous)e(cases)j(is)h(f)o(airly)e(small)g(and)g(analyzing)
f(more)g(te)o(xts)-150 540 y(and)h(concentrating)e(on)j(cases)g(where)f
(the)h(current)f(rule)g(mak)o(es)h(an)-150 631 y(incorrect)19
b(prediction)f(may)i(lead)g(us)h(to)f(a)h(more)e(rob)n(ust)h(rule.)605
812 y Fh(Conclusions)-150 930 y Fl(Pronouns)28 b(occur)g(frequently)f
(in)j(te)o(xts)g(and)f(ha)n(v)o(e)f(been)h(hypothe-)-150
1021 y(sized)k(to)f(play)g(a)h(lar)o(ge)e(role)h(in)h(te)o(xt)f
(coherence.)60 b(Y)-8 b(et,)35 b(pronoun)-150 1112 y(generation)29
b(has)i(not)f(been)g(studied)g(in)h(detail.)56 b(If)31
b(future)e(natural)-150 1204 y(language)d(generation)g(systems)j(are)e
(to)h(produce)e(coherent,)i(natu-)-150 1295 y(ral)33
b(te)o(xts,)j(the)o(y)c(must)h(use)h(rules)f(for)f(generating)f
(pronouns)f(that)-150 1386 y(produce)h(pronouns)f(in)k(roughly)c(the)j
(same)g(places)g(that)g(human-)-150 1478 y(produced)21
b(te)o(xts)i(do.)33 b(Moreo)o(v)o(er)m(,)20 b(the)j(rules)g(must)h(be)e
(based)h(on)g(in-)-150 1569 y(formation)18 b(that)j(w)o(ould)e(be)h(a)n
(v)n(ailable)g(to)g(a)h(sentence)f(generator)-5 b(.)23
b(At)-150 1660 y(the)g(same)f(time,)h(in)g(order)e(to)i(e)n(v)n(aluate)
e(rules,)i(the)o(y)f(must)h(be)f(based)-150 1752 y(on)e(information)e
(that)i(can)g(be)g(gleaned)f(from)g(a)i(te)o(xt.)-67
1843 y(In)16 b(this)g(w)o(ork)g(we)g(ha)n(v)o(e)g(ar)o(gued)e(that)i
(changes)f(in)h(setting,)g(as)h(indi-)-150 1935 y(cated)j(by)g(changes)
g(in)h(time,)f(pro)o(vide)f(an)h(e)o(xplanation)e(for)i(patterns)-150
2026 y(of)27 b(pronoun)e(use)i(in)h(naturally)e(occurring)f(te)o(xt.)46
b(That)27 b(is,)j(e)n(v)o(en)c(in)-150 2117 y(places)32
b(where)f(a)h(pronoun)d(w)o(ould)i(be)h(unambiguous,)g(a)g(de\002nite)
-150 2209 y(description)27 b(might)h(be)g(used)h(when)f(the)g(time)h
(of)f(the)h(sentence)f(is)-150 2300 y(dif)n(ferent)20
b(from)g(the)i(time)g(of)f(the)h(sentence)f(in)g(which)h(the)f(pre)n
(vious)-150 2391 y(mention)g(w)o(as)j(made.)32 b(This)22
b(hypothesis)f(pro)o(vides)g(an)i(e)o(xplanation)-150
2483 y(for)16 b(man)o(y)f(of)h(the)g(uses)h(of)f(de\002nite)g
(descriptions)f(found)g(in)i(the)f(stud-)-150 2574 y(ied)j(te)o(xts.)24
b(Other)19 b(uses)g(of)f(de\002nite)h(descriptions)e(occur)h(because)g
(of)-150 2665 y(ambiguities.)23 b(W)-7 b(e)20 b(ha)n(v)o(e)e(suggested)
g(a)h(rule)g(which)f(addresses)g(when)-150 2757 y(such)h(ambiguities)f
(should)g(not)g(preclude)g(the)h(generation)e(of)h(a)i(pro-)-150
2848 y(noun.)j(Our)d(scheme)f(appears)g(to)h(be)g(a)g(reasonable)f(e)o
(xplanation)e(for)-150 2939 y(the)j(patterns)g(of)g(pronoun)d(use)k
(found)d(in)i(our)g(corpus.)-150 3154 y Fj(Ackno)o(wledgments.)82
b Fl(This)20 b(w)o(ork)g(w)o(as)g(done)f(while)h(the)g(\002rst)h(au-)
-150 3245 y(thor)i(w)o(as)h(visiting)f(the)h(Institute)f(for)g
(Research)g(in)h(Cogniti)n(v)o(e)e(Sci-)-150 3337 y(ence)h(and)f(while)
h(the)g(second)f(author)f(w)o(as)j(a)f(post-doctoral)e(fello)n(w)-150
3428 y(there)i(\(NSF)h(SBR)h(8920230\).)31 b(W)-7 b(e)25
b(w)o(ould)e(lik)o(e)g(to)h(thank)f(Jennifer)-150 3519
y(Arnold)f(and)g(the)h(centering)f(group)f(at)j(UPenn)f(for)f(helpful)g
(discus-)-150 3611 y(sions.)i(W)-7 b(e)18 b(w)o(ould)e(also)i(lik)o(e)f
(to)g(thank)f(the)h(anon)o(ymous)d(re)n(vie)n(wers.)631
3792 y Fh(Refer)n(ences)-150 3893 y Fi(Appelt,)29 b(D.)g(E.)g
(\(1981\).)61 b Fc(Planning)30 b(Natur)o(al-Langua)o(g)o(e)i(Utter)o
(ances)e(to)16 3968 y(Satisfy)g(Multiple)h(Goals)p Fi(,)i(\(Ph.D.)c
(thesis\).)63 b(Stanford)31 b(Uni)n(v)o(ersity)-5 b(.)16
4042 y(Also)40 b(appeared)h(as:)65 b(SRI)38 b(International)j(T)-5
b(echnical)40 b(Note)f(259,)16 4117 y(March)20 b(1982.)-150
4192 y(Appelt,)g(D.)g(E.)g(\(1985\).)33 b(Planning)21
b(English)f(referring)h(e)o(xpressions.)33 b Fc(Arti-)16
4267 y(\002cial)19 b(Intellig)o(ence)p Fi(,)h(26\(1\):1\22633.)-150
4341 y(Arnold,)15 b(J.)f(E.)g(\(1998\).)19 b Fc(Refer)m(ence)c(F)-8
b(orm)15 b(and)h(Discour)o(se)g(P)-6 b(atterns)p Fi(,)15
b(\(Ph.D.)16 4416 y(thesis\).)27 b(Stanford)19 b(Uni)n(v)o(ersity)-5
b(,)19 b(Department)g(of)g(Linguistics.)-150 4491 y(Brennan,)29
b(S.)e(E.,)i(M.)f(W)-7 b(.)27 b(Friedman)i(&)f(C.)f(J.)h(Pollard)f
(\(1987\).)58 b(A)27 b(cen-)16 4579 y(tering)d(approach)h(to)e
(pronouns.)43 b(In)24 b Fc(Pr)m(oceedings)g(of)g(the)f(25)1679
4547 y Fa(th)1767 4579 y Fc(An-)16 4653 y(nual)15 b(Meeting)h(of)e(the)
h(Association)g(for)g(Computational)g(Linguistics,)16
4728 y Fi(Stanford,)k(Cal.,)f(6\2269)h(July)h(1987,)f(pp.)g
(155\226162.)-150 4803 y(Dale,)24 b(R.)h(\(1992\).)46
b Fc(Gener)o(ating)26 b(Referring)f(Expr)m(essions:)37
b(Constructing)16 4878 y(Descriptions)30 b(in)f(a)g(Domain)h(of)f
(Objects)g(and)h(Pr)m(ocesses)p Fi(.)60 b(Cam-)16 4952
y(bridge,)19 b(Mass.:)24 b(MIT)18 b(Press.)-150 5027
y(Dale,)25 b(R.)f(&)h(E.)f(Reiter)g(\(1995\).)47 b(Computational)26
b(interpretations)g(of)f(the)16 5102 y(Gricean)34 b(maxims)f(in)g(the)h
(generation)g(of)f(referring)h(e)o(xpressions.)16 5176
y Fc(Co)o(gnitive)20 b(Science)p Fi(,)f(18:233\226263.)-150
5251 y(Genette,)31 b(G.)g(\(1980\).)69 b Fc(Narr)o(ative)32
b(Discour)o(se:)49 b(An)32 b(Essay)g(in)f(Method)p Fi(.)16
5326 y(Ithaca,)19 b(N.Y)-10 b(.:)22 b(Cornell)d(Uni)n(v)o(ersity)g
(Press.)-150 5401 y(Gi)n(v)o(on,)j(T)-6 b(.)22 b(\(1983\).)39
b(T)-6 b(opic)23 b(continuity)g(in)g(spok)o(en)h(English.)38
b(In)23 b(T)-6 b(.)22 b(Gi)n(v)o(on)16 5475 y(\(Ed.\),)29
b Fc(T)-7 b(opic)28 b(Continuity)g(in)g(Discour)o(se:)42
b(A)28 b(Quantitative)g(Cr)m(oss-)16 5550 y(Langua)o(g)o(e)21
b(Study)p Fi(.)e(Amsterdam,)g(Philadelphia:)24 b(John)c(Benjamins.)2025
83 y(Gordon,)38 b(P)-8 b(.)37 b(C.)g(&)h(R.)f(Hendrick)h(\(1998\).)89
b(The)37 b(representation)i(and)2191 158 y(processing)34
b(of)f(coreference)h(in)e(discourse.)72 b Fc(Co)o(gnitive)33
b(Science)p Fi(,)2191 232 y(22\(4\):389\226424.)2025
307 y(Grosz,)15 b(B.)g(J.,)g(A.)g(K.)g(Joshi)g(&)h(S.)e(W)-6
b(einstein)15 b(\(1995\).)20 b(Centering:)i(A)15 b(frame-)2191
382 y(w)o(ork)23 b(for)f(modeling)i(the)e(local)h(coherence)h(of)e
(discourse.)39 b Fc(Compu-)2191 457 y(tational)19 b(Linguistics)p
Fi(,)g(21\(2\):203\226225.)2025 531 y(Grosz,)25 b(B.)f(J.)g(&)h(C.)f
(L.)g(Sidner)g(\(1986\).)47 b(Attention,)26 b(intentions,)g(and)g(the)
2191 606 y(structure)20 b(of)g(discourse.)30 b Fc(Computational)21
b(Linguistics)p Fi(,)e(12\(3\):175\226)2191 681 y(204.)2025
756 y(Kame)o(yama,)k(M.)f(\(1998\).)39 b(Intrasentential)23
b(centering:)31 b(A)22 b(case)h(study)-5 b(.)39 b(In)2191
830 y(M.)32 b(W)-6 b(alk)o(er)m(,)36 b(A.)31 b(Joshi)i(&)f(E.)g(Prince)
g(\(Eds.\),)i Fc(Centering)f(Theory)2191 905 y(in)28
b(Discour)o(se)p Fi(,)k(pp.)c(89\226112.)i(Oxford,)h(U.K.:)41
b(Oxford)29 b(Uni)n(v)o(ersity)2191 980 y(Press.)2025
1054 y(McDonald,)24 b(D.)f(D.)f(\(1980\).)42 b Fc(Natur)o(al)23
b(Langua)o(g)o(e)j(Pr)m(oduction)e(as)f(a)g(Pr)m(o-)2191
1129 y(cess)35 b(of)g(Decision)g(Making)h(Under)f(Constr)o(aint)p
Fi(,)k(\(Ph.D.)33 b(thesis\).)2191 1204 y(MIT)-6 b(.)2025
1279 y(McK)n(eo)n(wn,)20 b(K.)e(R.)g(\(1983\).)27 b(F)o(ocus)19
b(constraints)g(on)h(language)g(generation.)2191 1369
y(In)27 b Fc(Pr)m(oceedings)i(of)e(the)h(8)2919 1338
y Fa(th)3010 1369 y Fc(International)h(J)n(oint)e(Confer)m(ence)i(on)
2191 1444 y(Arti\002cial)23 b(Intellig)o(ence)o(,)i Fi(Karlsruhe,)f
(German)o(y)-5 b(,)25 b(August)e(1983,)j(pp.)2191 1519
y(582\226587.)2025 1594 y(McK)n(eo)n(wn,)21 b(K.)d(R.)h(\(1985\).)30
b Fc(T)-7 b(e)o(xt)18 b(Gener)o(ation:)26 b(Using)19
b(Discour)o(se)i(Str)o(ate-)2191 1668 y(gies)35 b(and)g(F)-8
b(ocus)35 b(Constr)o(aints)g(to)g(Gener)o(ate)g(Natur)o(al)g(Langua)o
(g)o(e)2191 1743 y(T)-7 b(e)o(xt)p Fi(.)26 b(Cambridge,)19
b(U.K.:)k(Cambridge)c(Uni)n(v)o(ersity)g(Press.)2025
1818 y(Moens,)d(M.)f(&)g(M.)g(Steedman)g(\(1988\).)20
b(T)-5 b(emporal)15 b(ontology)i(and)e(temporal)2191
1892 y(reference.)28 b Fc(Computational)20 b(Linguistics)p
Fi(,)e(14\(2\):15\22628.)2025 1967 y(Nakhimo)o(vsk)o(y)-5
b(,)22 b(A.)d(\(1988\).)32 b(Aspect,)20 b(aspectual)h(class,)f(and)h
(the)f(temporal)2191 2042 y(structure)28 b(of)f(narrati)n(v)o(e.)54
b Fc(Computational)28 b(Linguistics)p Fi(,)h(14\(2\):29\226)2191
2117 y(43.)2025 2191 y(P)o(assonneau,)19 b(R.)e(\(1996\).)26
b(Using)18 b(centering)g(to)g(relax)g(Gricean)g(constraints)2191
2266 y(on)h(disocurse)h(anaphoric)h(noun)f(ophrases.)28
b Fc(Langua)o(g)o(e)21 b(and)f(Speec)o(h)p Fi(,)2191
2341 y(39\(2\):229\226264.)2025 2415 y(Prince,)f(G.)g(\(1982\).)29
b Fc(Narr)o(atolo)o(gy:)d(The)19 b(F)-8 b(orm)19 b(and)i(Functioning)f
(of)f(Nar)o(-)2191 2490 y(r)o(ative)p Fi(.)27 b(Berlin:)c(Mouton.)2025
2565 y(Reichman,)g(R.)f(\(1985\).)39 b Fc(Getting)22
b(Computer)o(s)i(to)e(T)-7 b(alk)22 b(lik)o(e)h(Y)-7
b(ou)23 b(and)g(Me)p Fi(.)2191 2640 y(Cambridge,)c(Mass.:)24
b(MIT)18 b(Press.)2025 2714 y(Reiter)m(,)k(E.)h(\(1990\).)42
b(Generating)24 b(descriptions)g(that)f(e)o(xploit)h(a)f(user')l(s)g
(do-)2191 2789 y(main)j(kno)n(wledge.)51 b(In)26 b(R.)f(Dale,)i(C.)e
(Mellish)h(&)g(M.)g(Zock)g(\(Eds.\),)2191 2864 y Fc(Curr)m(ent)g
(Resear)m(c)o(h)h(in)f(Natur)o(al)g(Langua)o(g)o(e)h(Gener)o(ation)p
Fi(.)g(London:)2191 2938 y(Academic)20 b(Press.)2025
3013 y(Sidner)m(,)30 b(C.)g(L.)g(\(1979\).)65 b Fc(T)-7
b(owar)m(ds)31 b(a)g(Computational)g(Theory)g(of)g(De\002-)2191
3088 y(nite)26 b(Anaphor)o(a)i(Compr)m(ehension)g(in)f(English)p
Fi(.)50 b(T)-5 b(echnical)27 b(Report)2191 3163 y(AI-Memo)c(537,)h
(Cambridge,)g(Mass.:)30 b(Massachusetts)24 b(Institute)e(of)2191
3237 y(T)-5 b(echnology)g(,)20 b(AI)f(Lab)m(.)2025 3312
y(Strube,)26 b(M.)h(\(1998\).)52 b(Ne)n(v)o(er)27 b(look)h(back:)39
b(An)27 b(alternati)n(v)o(e)g(to)f(centering.)2191 3403
y(In)20 b Fc(Pr)m(oceedings)h(of)f(the)g(17)2929 3371
y Fa(th)3014 3403 y Fc(International)h(Confer)m(ence)g(on)g(Com-)2191
3493 y(putational)34 b(Linguistics)f(and)g(36)3112 3461
y Fa(th)3209 3493 y Fc(Annual)h(Meeting)g(of)e(the)h(As-)2191
3568 y(sociation)f(for)g(Computational)h(Linguistics,)h
Fi(Montr)t(\264)-29 b(eal,)35 b(Qu)t(\264)-29 b(ebec,)2191
3642 y(Canada,)19 b(10\22614)i(August)f(1998,)f(V)-10
b(ol.)19 b(2,)g(pp.)g(1251\2261257.)2025 3717 y(Strube,)j(M.)h(&)g(U.)f
(Hahn)i(\(1997\).)40 b(Centered)23 b(se)o(gmentation:)33
b(Scaling)22 b(up)2191 3792 y(the)16 b(centering)g(model)g(to)f(global)
h(referential)g(discourse)g(structure.)k(In)2191 3883
y Fc(Pr)m(oceedings)27 b(of)e(the)h(19)2861 3851 y Fa(th)2951
3883 y Fc(Annual)h(Confer)m(ence)g(of)e(the)h(Co)o(gnitive)2191
3957 y(Science)20 b(Society)l(,)f Fi(P)o(alo)f(Alto,)h(Cal.,)e(7\22610)
k(August)e(1997.)2025 4032 y(Suri,)28 b(L.)f(Z.)h(&)h(K.)e(F)-6
b(.)28 b(McCo)o(y)i(\(1994\).)59 b(RAFT/RAPR)26 b(and)j(centering:)2191
4107 y(A)23 b(comparison)i(and)f(discussion)h(of)f(problems)g(related)g
(to)f(process-)2191 4182 y(ing)15 b(comple)o(x)g(sentences.)j
Fc(Computational)e(Linguistics)p Fi(,)f(20\(2\):301\226)2191
4256 y(317.)2025 4331 y(V)-10 b(ogt,)29 b(J.)g(\(1990\).)60
b Fc(Aspekte)29 b(erz)6 b(\250)-31 b(ahlender)31 b(Pr)m(osa:)44
b(Eine)29 b(Einf)6 b(\250)-31 b(uhrung)30 b(in)2191 4422
y(Erz)6 b(\250)-31 b(ahltec)o(hnik)28 b(und)h(Romantheorie)f
Fi(\(7)3284 4390 y Fa(th)3376 4422 y Fi(ed.\).)54 b(Opladen:)42
b(W)-6 b(est-)2191 4496 y(deutscher)20 b(V)-8 b(erlag.)2025
4571 y(V)e(onk,)25 b(W)-7 b(.,)25 b(L.)e(G.)h(Hustinx)g(&)h(W)-7
b(.)23 b(H.)h(Simons)g(\(1992\).)45 b(The)24 b(use)h(of)f(ref-)2191
4646 y(erential)k(e)o(xpressions)h(in)f(structuring)h(discourse.)57
b Fc(Langua)o(g)o(e)30 b(and)2191 4721 y(Co)o(gnitive)20
b(Pr)m(ocesses)p Fi(,)e(7\(3/4\):301\226333.)2025 4795
y(W)-6 b(ebber)m(,)22 b(B.)g(L.)f(\(1988\).)38 b(T)-5
b(ense)23 b(as)f(discourse)h(anaphor)l(.)39 b Fc(Computational)2191
4870 y(Linguistics)p Fi(,)18 b(14\(2\):61\22673.)2025
4945 y(W)-6 b(ebber)m(,)30 b(B.)g(L.)f(\(1991\).)64 b(Structure)30
b(and)h(ostension)g(in)f(the)h(interpreta-)2191 5020
y(tion)24 b(of)g(discourse)i(deixis.)44 b Fc(Langua)o(g)o(e)26
b(and)f(Co)o(gnitive)g(Pr)m(ocesses)p Fi(,)2191 5094
y(6\(2\):107\226135.)2025 5169 y(W)m(iebe,)18 b(J.)g(M.)h(\(1994\).)27
b(T)m(racking)19 b(point)g(of)g(vie)n(w)f(in)h(narrati)n(v)o(e.)26
b Fc(Computa-)2191 5244 y(tional)19 b(Linguistics)p Fi(,)f
(20\(2\):233\226287.)p eop
%%Trailer
end
userdict /end-hook known{end-hook}if
%%EOF