Notes on computational linguistics.pdf - UCLA Department of ...

Stabler - Lx 185/209 2003
(3) Dalrymple and Kaplan (2000), Bayer and Johnson (1995), Ingria (1990), and others have pointed out that
agreement seems not always to have the “two way” character of unification. That is, while in English,
an ambiguous word can be resolved only in one way, this is not always true:
a. The English fish is ambiguous between singular and plural, and cannot be both:
The fish who eats the food gets/*get fat
Thefishwhoeatthefood*gets/getfat
(This is what we expect if fish has a number feature that gets unified with one particular value.)
b. The Polish wh-pronoun kogo is ambiguous between accusative and genitive case, and can be both:
Kogo
who
Janek lubi a Jerzy nienawidzi?
Janek likes and Jerzy hates
c.
(lubi requires acc object and nienawidzi requires gen object.)
The German was is ambiguous between accusative and nominative case, and can be both:
Ich habe gegessen was übrig war.
I have eaten what left was
(The German gegessen requires acc object and übrig war needs a nom subject.)
Dalrymple and Kaplan (2000) propose that what examples like the last two show is that feature values
should not be atoms like sg, pl or nom, acc, gen but (at least in some cases) sets of atoms.
3.2 More unification grammars: case features
(4) We can easily extend the grammar g2.pl to require subjects to have nominative case and objects,
accusative case, just by adding a case argument to dp:
% g3.pl
:- op(1200,xfx,:˜).
ip :˜ [dp(P,N,nom), i1(P,N)]. i1(P,N) :˜ [i0, vp(P,N)]. i0 :˜ [].
dp(1,s,nom) :˜ [’I’]. dp(2,_,_) :˜ [you]. dp(3,s,nom) :˜ [she].
dp(3,s,nom) :˜ [he].
dp(3,s,_) :˜ [it].
dp(3,p,nom) :˜ [they].
dp(1,s,acc) :˜ [’me’]. dp(3,s,acc) :˜ [her].
dp(3,s,acc) :˜ [him].
dp(3,p,acc) :˜ [them].
dp(3,s,_) :˜ [titus]. dp(3,s,_) :˜ [tamora]. dp(3,s,_) :˜ [lavinia].
dp(3,N,_) :˜ [d1(N)]. d1(N) :˜ [d0(N), np(N)]. d0(_) :˜ [the].
d0(p) :˜ [most].
d0(s) :˜ [every]. d0(s) :˜ [some]. d0(p) :˜ [few].
np(N) :˜ [n1(N)]. n1(N) :˜ [n0(N)]. n0(s) :˜ [penguin].
n0(p) :˜ [penguins].
n0(s) :˜ [song]. n0(p) :˜ [songs].
vp(P,N) :˜ [v1(P,N)]. v1(P,N) :˜ [v0(intrans,P,N)].
v1(P,N) :˜ [v0(trans,P,N),dp(_,_,acc)].
v0(_,1,_) :˜ [sing]. v0(_,2,_) :˜ [sing]. v0(_,3,s) :˜ [sings].
v0(_,3,p) :˜ [sing].
v0(trans,1,_) :˜ [praise]. v0(trans,2,_) :˜ [praise]. v0(trans,3,s) :˜ [praises].
v0(trans,3,p) :˜ [praise].
v0(intrans,1,_) :˜ [laugh]. v0(intrans,2,_) :˜ [laugh]. v0(intrans,3,s) :˜ [laughs].
v0(intrans,3,p) :˜ [laugh].
(5) The coordinate structure Tamora and Lavinia is plural. We cannot get this kind of construction with
rules like the following because they are left recursive, and so problematic for TD:
dp(_,p,K) :˜ [dp(_,_,K), coord(dp(_,_,K))]. % nb: left recursion
vp(P,N) :˜ [vp(P,N), coord(vp(P,N))]. % nb: left recursion
coord(Cat) :˜ [and,Cat].
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