prolog natural language parsing

i have a college assignment to make a prolog program parse natural language, ie it should output

P = np(det(the), np2(noun(cat))), vp(verb(sat), pp(prep(on), np(det(the), np2(noun(mat)))))
L = []

when i input np([the, cat, sat, on, the, mat],P,L).

instead, the verb and noun phrases are being sp开发者_运维百科lit and coming out seperatly, like:

P = np(det(the), np2(noun(cat))),
L = [sat, on, the, mat]

i was wondering if anyone could point out where i am going wrong, it would be most appreciated, my code is:

sentence(Sentence,sentence(np(Noun_Phrase)), (vp(Verb_Phrase))):-
/* so take a sentence (first arg) and parse it into a noun phrase and a verb phase */
    np(Sentence,Noun_Phrase, Rem),
    vp(Rem, Verb_Phrase).

np([X|T],np(det(X),NP2),Rem):-
    det(X),
    np2(T,NP2,Rem).
np(Sentence,Parse,Rem):- np2(Sentence,Parse,Rem).
np(Sentence,np(NP,PP),Rem):-
    np(Sentence,NP,Rem1),
    pp(Rem1,PP,Rem).

np2([H|T],np2(noun(H)),T):- noun(H).  
np2([H|T],np2(adj(H),Rest),Rem):- adj(H),np2(T,Rest,Rem).  
pp([H|T],pp(prep(H),Parse),Rem):-
    prep(H),
    np(T,Parse,Rem).

vp([H|[]],vp(verb(H))):- verb(H).
vp([H|Rest],vp(verb(H),RestParsed),Rem):- verb(H), pp(Rest, RestParsed, Rem).
vp([H|Rest],vp(verb(H),RestParsed),Rem):- verb(H), np(Rest, RestParsed, Rem).

det(the).
det(with).
noun(cat).
noun(mat).
noun(mouse).
noun(rabbit).
noun(moon).
verb(sat).
verb(ate).
verb(ran_away).
prep(on).
adj(big).
adj(fat).
adj(comfy).
adj(yellow).
adj(silvery).
adj(orange).

Well, are you really sure you want to get NP for "the cat sat on the mat". This isn't an NP, it's a full sentence, isn't?

Secondly I haven't written in Prolog for quite a some time. I think the code should be something along these lines:

sentence(S, sentence(np(NP), vp(VP))) :-
    np(S, NP, R),
    vp(R, VP, []). /* Changed here - added the third argument */

np([X | S], np(det(X), NP2), R) :-
    det(X),
    np2(S, NP2, R).
np(S, NP, R) :- 
    np2(S, NP, R).
np(S, np(NP, PP), R) :-
    append(X, Y, S), /* Changed here - otherwise possible endless recursion */
    pp(Y, PP, R),
    np(X, NP, []).

np2([X | R], np2(noun(X)), R) :- 
    noun(X).
np2([X | S], np2(adj(X), NP), R) :- 
    adj(X),
    np2(S, NP, R).

pp([X | S], pp(prep(X), NP), R):-
    prep(X),
    np(S, NP, R).

vp([X | R], vp(verb(X)), R) :- /* Changed here - added the third argument */
    verb(X).
vp([X | S], vp(verb(X), PP), R) :- 
    verb(X), 
    pp(S, PP, R).
vp([X | S], vp(verb(X), NP), R) :- 
    verb(X), 
    np(S, NP, R).

det(the).
det(with).
...

Sorry for the changed names. I wasn't able to work with the code the way it was.

After carefully looking through your code, I've noticed at least two errors.

First and most importantly, you need to be more careful how you define your 'vp' predicate, I noticed you've defined two different versions which don't do the same things. You can tell they're different because one is only arity 2 while the other is arity 3.

I suggest defining all the important and functional 'vp' predicate definitions as arity 3, preserving the "Tail" parameter, then using a single arity 2 predicate that looks like this:

vp(T, Parse) :- vp(T, Parse, []).

Second, I think you need to check how you've nested your brackets in your definition of the 'sentence' predicate. I think you've mixed up a couple of them.