NotEquivalent

src/prolog/builtins/unificationOperators.kt

@@ -55,3 +55,12 @@ class Equivalent(private val term1: Term, private val term2: Term) : Operator(At
         applySubstitution(term2, subs)
     )
 }
+
+class NotEquivalent(private val term1: Term, private val term2: Term) : Operator(Atom("\\=="), term1, term2) {
+    private val not = Not(Equivalent(term1, term2))
+    override fun satisfy(subs: Substitutions): Answers = not.satisfy(subs)
+    override fun applySubstitution(subs: Substitutions): NotEquivalent = NotEquivalent(
+        applySubstitution(term1, subs),
+        applySubstitution(term2, subs)
+    )
+}