What does \+ mean in Prolog? It’s the ‘not provable‘ operator. It succeeds if its argument is not provable (and fails if its argument is provable). Related Posts: “Not equal” sign in Visual Prolog? singleton variables in prolog Prolog – Arguments are not sufficiently instantiated ‘if’ in prolog? “Syntax error: Operator expected” in Prolog How do I append lists in Prolog? Reversing a List in Prolog List Length in Prolog Prolog “or” operator, query
