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

Stabler - Lx 185/209 2003
(11) We can implement this in SWI-prolog as follows:
/*
* file: recognize.pl
*/
:- op(1200,xfx,:˜). % this is our object language "if"
:- op(1100,xfx,?˜).
[] ?˜ [].
% metalanguage provability predicate
(S0 ?˜ Goals0) :- infer(S0,Goals0,S,Goals), (S ?˜ Goals).
infer(S,[A|C], S,DC) :- (A :˜ D), append(D,C,DC). % ll
infer([A|S],[A|C], S,C). % scan
ip :˜ [dp, i1]. i1 :˜ [i0, vp]. i0 :˜ [will].
dp :˜ [d1]. d1 :˜ [d0, np]. d0 :˜ [the].
np :˜ [n1]. n1 :˜ [n0].
n1 :˜ [n0, cp].
n0 :˜ [idea].
vp :˜ [v1]. v1 :˜ [v0]. v0 :˜ [suffice].
cp :˜ [c1]. c1 :˜ [c0, ip]. c0 :˜ [that].
(12) Then we can have a session like this:
2% swiprolog
Welcome to SWI-Prolog (Version 3.2.9)
Copyright (c) 1993-1999 University of Amsterdam. All rights reserved.
For help, use ?- help(Topic). or ?- apropos(Word).
1 ?- [recognize].
recognize compiled, 0.01 sec, 3,128 bytes.
Yes
2 ?- [the,idea,will,suffice] ?˜ [ip].
Yes
3 ?- [idea,the,will] ?˜ [ip].
No
4 ?- [idea] ?˜ [Cat].
Cat = np ;
Cat = n1 ;
Cat = n0 ;
Cat = idea ;
No
5 ?- [will,suffice] ?˜ [Cat].
Cat = i1 ;
No
6 ?- [will,suffice,will,suffice] ?˜ [C,D].
C = i1
D = i1 ;
No
7 ?- S ?˜ [ip].
S = [the, idea, will, suffice] ;
S = [the, idea, will, v0] ;
S = [the, idea, will, v1]
Yes
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