giles
09683b8a18
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25 lines
532 B
Prolog
25 lines
532 B
Prolog
%% family — facts + transitive ancestor + derived relations.
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%% Five-generation tree: tom -> bob -> {ann, pat} -> jim, plus tom's
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%% other child liz.
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parent(tom, bob).
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parent(tom, liz).
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parent(bob, ann).
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parent(bob, pat).
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parent(pat, jim).
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male(tom).
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male(bob).
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male(jim).
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male(pat).
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female(liz).
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female(ann).
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father(F, C) :- parent(F, C), male(F).
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mother(M, C) :- parent(M, C), female(M).
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ancestor(X, Y) :- parent(X, Y).
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ancestor(X, Y) :- parent(X, Z), ancestor(Z, Y).
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sibling(X, Y) :- parent(P, X), parent(P, Y), \=(X, Y).
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