Given a parse tree of a string my goal is to update my knowledge base.
From a sentence with variable length like the following:
"node 1 is near node 2 that is near node 3 that is near node 4 that..."
in my representation becomes a parse tree representation of the sentence, for example:
s(desc(np(noun(node),id(1)),vp(verb(is),prep(near),np(noun(node),id(2),rel_clause(rel(that)...
from which I'd like to extract and assert the following informations:
edge(1,2),edge(2,3),edge(3,4).
How can I achieve this goal?
I've tried to manage some case with something like
:- dynamic edge/2.
extract(T):- T= s(desc(np(noun(node),id(A)),vp(verb(is),prep(near),np(noun(node),id(B)))),
assert(edge(A,B)).
extract(T):- T= s(desc(np(noun(node),id(A)),vp(verb(is),prep(near),np(noun(node),id(B),rel_clause(rel(that)...
etc
but I'd like to manage potential infinite sentences.
I'm using SWI-prolog.
EDIT:
complete example of a parse tree I get in input:
desc(np(noun(node), id(1)), vp(verb(is), prep(near), np(noun(node), id(2),
rel_clause(rel(that), vp(verb(is), prep(near), np(noun(node), id(3),
rel_clause(rel(that), vp(verb(is), prep(near), np(noun(node), id(4)))))))))
The first thing to do is come up with a more useable description of your data. One way is to break it down like this:
description = desc(subject, verb_part)
subject = np(noun(node), id(A))
verb_part = vp(verb(is), prep(near), object_part)
object_part = np(noun(node), id(B))
object_part = np(noun(node), id(B), rel_part)
rel_part = relcl(rel(that), verb_part)
From here, you can see where the recursion occurs and write predicates which align with the definitions above:
% description = desc(subject, verb_part)
% subject = np(noun(node), id(A))
%
extract(desc(np(noun(node), id(A)), VerbPart)) :-
select_edge(A, VerbPart).
% verb_part = vp(verb(is), prep(near), object_part)
%
select_edge(A, vp(verb(is), prep(near), ObjectPart)) :-
connect_node(A, ObjectPart).
% object_part = np(noun(node), id(B))
%
connect_node(A, np(noun(node), id(B))) :-
assertz(edge(A, B)).
% object_part = np(noun(node), id(B), rel_part)
% rel_part = relcl(rel(that), verb_part)
%
connect_node(A, np(noun(node), id(B), relcl(rel(that), VerbPart))) :-
assertz(edge(A, B)),
select_edge(B, VerbPart).
To execute:
| ?- extract(desc(np(noun(node), id(1)), vp(verb(is), prep(near), np(noun(node), id(2),
relcl(rel(that), vp(verb(is), prep(near), np(noun(node), id(3),
relcl(rel(that), vp(verb(is), prep(near), np(noun(node), id(4))))))))))).
true ? ;
no
The results are asserted, as can be seen if we list the edge/2 facts:
| ?- listing(edge).
% file: user_input
edge(1, 2).
edge(2, 3).
edge(3, 4).
yes
You can also collect the edges in a list instead of asserting them, and have a result of the query be, [edge(1,2), edge(2,3), edge(3,4)]:
extract(desc(np(noun(node), id(A)), VerbPart), Edges) :-
select_edge(A, VerbPart, Edges).
select_edge(A, vp(verb(is), prep(near), ObjectPart), Edges) :-
connect_node(A, ObjectPart, Edges).
connect_node(A, np(noun(node), id(B)), [edge(A,B)]).
connect_node(A, np(noun(node), id(B), relcl(rel(that), VerbPart)), [edge(A,B)|Edges]) :-
select_edge(B, VerbPart, Edges).
And then assert them all at once from the resulting list with maplist:
extract(Description, Edges), maplist(assertz, Edges).
