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variant(?Term1, ?Term2)
Succeeds if Term1 is a variant of Term2.
- ?Term1
- An arbitrary term.
- ?Term2
- An arbitrary term.
Description
Succeeds if the given terms are equal in the sense that all
ground instantiations in Term1 are also instantiations in Term2 and vice
versa. The result is undefined if Term1 and Term2 share variables. No
unification is performed.
Fail Conditions
Fails if Term1 is not a variant of Term2.
Resatisfiable
No
Examples
Success:
variant(1,1).
variant(X,Y).
variant(f(a,b),f(a,b)).
variant(f(a,X),f(a,Y)).
variant(f(X,Y),f(Y,X)).
variant([X,2], [Y,2]).
Fail:
variant(f(a,b),f(a,Y)).
variant(f(a,X),f(a,b)).
variant(f(X,Y),f(Z,Z)).
See Also
instance / 2, compare_instances / 3, prune_instances / 2