fact: Example F4: Formula L := orH (forallH 1 (equal (var 0) (var 1))) (existH 0 (existH 1 (notH (equal (var 0) (var 1))))).
imports: Coq(Arith Lists.List) hydras.Ackermann(fol folProp folProof Languages folLogic folLogic2 folLogic3 subAll Deduction primRec)