A goal ! that always succeeds. Once satisfied, disallows:
- Backtracking over the cut
- Backtracking and applying a different clause to same predicate to satisfy present goal Trims derivation tree of other choices on the way up to and including point in derivation tree.
Example
q(x) :- even(X), a(X).
q(x) :- odd(X), b(X).
% optimized with cut
q(x) :- even(X), !, a(X).
q(x) :- odd(X), b(X).