0.04/0.12 % Problem : theBenchmark.p : TPTP v0.0.0. Released v0.0.0. 0.04/0.13 % Command : twee %s --tstp --casc --quiet --explain-encoding --conditional-encoding if --smaller --drop-non-horn 0.13/0.34 % Computer : n013.cluster.edu 0.13/0.34 % Model : x86_64 x86_64 0.13/0.34 % CPU : Intel(R) Xeon(R) CPU E5-2620 v4 @ 2.10GHz 0.13/0.34 % Memory : 8042.1875MB 0.13/0.34 % OS : Linux 3.10.0-693.el7.x86_64 0.13/0.34 % CPULimit : 180 0.13/0.34 % DateTime : Thu Aug 29 13:11:01 EDT 2019 0.13/0.34 % CPUTime : 11.12/11.34 % SZS status Unsatisfiable 11.12/11.34 11.12/11.34 % SZS output start Proof 11.12/11.34 Take the following subset of the input axioms: 11.40/11.57 fof(condensed_detachment, axiom, ![X, Y]: true=ifeq(is_a_theorem(implies(X, Y)), true, ifeq(is_a_theorem(X), true, is_a_theorem(Y), true), true)). 11.40/11.57 fof(ifeq_axiom, axiom, ![B, A, C]: B=ifeq(A, A, B, C)). 11.40/11.57 fof(mv_1, axiom, ![X, Y]: is_a_theorem(implies(X, implies(Y, X)))=true). 11.40/11.57 fof(mv_2, axiom, ![X, Y, Z]: is_a_theorem(implies(implies(X, Y), implies(implies(Y, Z), implies(X, Z))))=true). 11.40/11.57 fof(mv_3, axiom, ![X, Y]: is_a_theorem(implies(implies(implies(X, Y), Y), implies(implies(Y, X), X)))=true). 11.40/11.57 fof(mv_5, axiom, ![X, Y]: is_a_theorem(implies(implies(not(X), not(Y)), implies(Y, X)))=true). 11.40/11.57 fof(prove_mv_33, negated_conjecture, is_a_theorem(implies(implies(not(a), b), implies(not(b), a)))!=true). 11.40/11.57 11.40/11.57 Now clausify the problem and encode Horn clauses using encoding 3 of 11.40/11.57 http://www.cse.chalmers.se/~nicsma/papers/horn.pdf. 11.40/11.57 We repeatedly replace C & s=t => u=v by the two clauses: 11.40/11.57 fresh(y, y, x1...xn) = u 11.40/11.57 C => fresh(s, t, x1...xn) = v 11.40/11.57 where fresh is a fresh function symbol and x1..xn are the free 11.40/11.57 variables of u and v. 11.40/11.57 A predicate p(X) is encoded as p(X)=true (this is sound, because the 11.40/11.57 input problem has no model of domain size 1). 11.40/11.57 11.40/11.57 The encoding turns the above axioms into the following unit equations and goals: 11.40/11.57 11.40/11.57 Axiom 1 (ifeq_axiom): X = ifeq(Y, Y, X, Z). 11.40/11.57 Axiom 2 (mv_1): is_a_theorem(implies(X, implies(Y, X))) = true. 11.40/11.57 Axiom 3 (condensed_detachment): true = ifeq(is_a_theorem(implies(X, Y)), true, ifeq(is_a_theorem(X), true, is_a_theorem(Y), true), true). 11.40/11.57 Axiom 4 (mv_3): is_a_theorem(implies(implies(implies(X, Y), Y), implies(implies(Y, X), X))) = true. 11.40/11.57 Axiom 5 (mv_5): is_a_theorem(implies(implies(not(X), not(Y)), implies(Y, X))) = true. 11.40/11.58 Axiom 6 (mv_2): is_a_theorem(implies(implies(X, Y), implies(implies(Y, Z), implies(X, Z)))) = true. 11.40/11.58 11.40/11.58 Lemma 7: ifeq(is_a_theorem(implies(X, Y)), true, is_a_theorem(implies(implies(Y, Z), implies(X, Z))), true) = true. 11.40/11.58 Proof: 11.40/11.58 ifeq(is_a_theorem(implies(X, Y)), true, is_a_theorem(implies(implies(Y, Z), implies(X, Z))), true) 11.40/11.58 = { by axiom 1 (ifeq_axiom) } 11.40/11.58 ifeq(true, true, ifeq(is_a_theorem(implies(X, Y)), true, is_a_theorem(implies(implies(Y, Z), implies(X, Z))), true), true) 11.40/11.58 = { by axiom 6 (mv_2) } 11.40/11.58 ifeq(is_a_theorem(implies(implies(X, Y), implies(implies(Y, Z), implies(X, Z)))), true, ifeq(is_a_theorem(implies(X, Y)), true, is_a_theorem(implies(implies(Y, Z), implies(X, Z))), true), true) 11.40/11.58 = { by axiom 3 (condensed_detachment) } 11.40/11.58 true 11.40/11.58 11.40/11.58 Lemma 8: is_a_theorem(implies(implies(implies(implies(X, Y), implies(Z, Y)), W), implies(implies(Z, X), W))) = true. 11.40/11.58 Proof: 11.40/11.58 is_a_theorem(implies(implies(implies(implies(X, Y), implies(Z, Y)), W), implies(implies(Z, X), W))) 11.40/11.58 = { by axiom 1 (ifeq_axiom) } 11.40/11.58 ifeq(true, true, is_a_theorem(implies(implies(implies(implies(X, Y), implies(Z, Y)), W), implies(implies(Z, X), W))), true) 11.40/11.58 = { by axiom 6 (mv_2) } 11.40/11.58 ifeq(is_a_theorem(implies(implies(Z, X), implies(implies(X, Y), implies(Z, Y)))), true, is_a_theorem(implies(implies(implies(implies(X, Y), implies(Z, Y)), W), implies(implies(Z, X), W))), true) 11.40/11.58 = { by lemma 7 } 11.40/11.58 true 11.40/11.58 11.40/11.58 Lemma 9: ifeq(is_a_theorem(implies(implies(X, implies(Y, X)), Z)), true, is_a_theorem(Z), true) = true. 11.40/11.58 Proof: 11.40/11.58 ifeq(is_a_theorem(implies(implies(X, implies(Y, X)), Z)), true, is_a_theorem(Z), true) 11.40/11.58 = { by axiom 1 (ifeq_axiom) } 11.40/11.58 ifeq(is_a_theorem(implies(implies(X, implies(Y, X)), Z)), true, ifeq(true, true, is_a_theorem(Z), true), true) 11.40/11.58 = { by axiom 2 (mv_1) } 11.40/11.58 ifeq(is_a_theorem(implies(implies(X, implies(Y, X)), Z)), true, ifeq(is_a_theorem(implies(X, implies(Y, X))), true, is_a_theorem(Z), true), true) 11.40/11.58 = { by axiom 3 (condensed_detachment) } 11.40/11.58 true 11.40/11.58 11.40/11.58 Lemma 10: ifeq(is_a_theorem(implies(implies(X, Y), Z)), true, is_a_theorem(implies(Y, Z)), true) = true. 11.40/11.58 Proof: 11.40/11.58 ifeq(is_a_theorem(implies(implies(X, Y), Z)), true, is_a_theorem(implies(Y, Z)), true) 11.40/11.58 = { by axiom 1 (ifeq_axiom) } 11.40/11.58 ifeq(true, true, ifeq(is_a_theorem(implies(implies(X, Y), Z)), true, is_a_theorem(implies(Y, Z)), true), true) 11.40/11.58 = { by lemma 9 } 11.40/11.58 ifeq(ifeq(is_a_theorem(implies(implies(Y, implies(X, Y)), implies(implies(implies(X, Y), Z), implies(Y, Z)))), true, is_a_theorem(implies(implies(implies(X, Y), Z), implies(Y, Z))), true), true, ifeq(is_a_theorem(implies(implies(X, Y), Z)), true, is_a_theorem(implies(Y, Z)), true), true) 11.40/11.58 = { by axiom 6 (mv_2) } 11.40/11.58 ifeq(ifeq(true, true, is_a_theorem(implies(implies(implies(X, Y), Z), implies(Y, Z))), true), true, ifeq(is_a_theorem(implies(implies(X, Y), Z)), true, is_a_theorem(implies(Y, Z)), true), true) 11.40/11.58 = { by axiom 1 (ifeq_axiom) } 11.40/11.58 ifeq(is_a_theorem(implies(implies(implies(X, Y), Z), implies(Y, Z))), true, ifeq(is_a_theorem(implies(implies(X, Y), Z)), true, is_a_theorem(implies(Y, Z)), true), true) 11.40/11.58 = { by axiom 3 (condensed_detachment) } 11.40/11.58 true 11.40/11.58 11.40/11.58 Lemma 11: is_a_theorem(implies(X, implies(implies(X, Y), Y))) = true. 11.40/11.58 Proof: 11.40/11.58 is_a_theorem(implies(X, implies(implies(X, Y), Y))) 11.40/11.58 = { by axiom 1 (ifeq_axiom) } 11.40/11.58 ifeq(true, true, is_a_theorem(implies(X, implies(implies(X, Y), Y))), true) 11.40/11.58 = { by axiom 4 (mv_3) } 11.40/11.58 ifeq(is_a_theorem(implies(implies(implies(Y, X), X), implies(implies(X, Y), Y))), true, is_a_theorem(implies(X, implies(implies(X, Y), Y))), true) 11.40/11.58 = { by lemma 10 } 11.40/11.58 true 11.40/11.58 11.40/11.58 Lemma 12: is_a_theorem(implies(implies(implies(implies(X, Y), Y), Z), implies(X, Z))) = true. 11.40/11.58 Proof: 11.40/11.58 is_a_theorem(implies(implies(implies(implies(X, Y), Y), Z), implies(X, Z))) 11.40/11.58 = { by axiom 1 (ifeq_axiom) } 11.40/11.58 ifeq(true, true, is_a_theorem(implies(implies(implies(implies(X, Y), Y), Z), implies(X, Z))), true) 11.40/11.58 = { by lemma 11 } 11.40/11.58 ifeq(is_a_theorem(implies(X, implies(implies(X, Y), Y))), true, is_a_theorem(implies(implies(implies(implies(X, Y), Y), Z), implies(X, Z))), true) 11.40/11.58 = { by lemma 7 } 11.40/11.58 true 11.40/11.58 11.40/11.58 Lemma 13: ifeq(is_a_theorem(implies(implies(implies(X, Y), implies(Z, Y)), W)), true, is_a_theorem(implies(implies(Z, X), W)), true) = true. 11.40/11.58 Proof: 11.40/11.58 ifeq(is_a_theorem(implies(implies(implies(X, Y), implies(Z, Y)), W)), true, is_a_theorem(implies(implies(Z, X), W)), true) 11.40/11.58 = { by axiom 1 (ifeq_axiom) } 11.40/11.58 ifeq(true, true, ifeq(is_a_theorem(implies(implies(implies(X, Y), implies(Z, Y)), W)), true, is_a_theorem(implies(implies(Z, X), W)), true), true) 11.40/11.58 = { by lemma 8 } 11.40/11.58 ifeq(is_a_theorem(implies(implies(implies(implies(X, Y), implies(Z, Y)), W), implies(implies(Z, X), W))), true, ifeq(is_a_theorem(implies(implies(implies(X, Y), implies(Z, Y)), W)), true, is_a_theorem(implies(implies(Z, X), W)), true), true) 11.40/11.58 = { by axiom 3 (condensed_detachment) } 11.65/11.82 true 11.65/11.82 11.65/11.82 Goal 1 (prove_mv_33): is_a_theorem(implies(implies(not(a), b), implies(not(b), a))) = true. 11.65/11.82 Proof: 11.65/11.82 is_a_theorem(implies(implies(not(a), b), implies(not(b), a))) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(true, true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 3 (condensed_detachment) } 11.65/11.82 ifeq(ifeq(is_a_theorem(implies(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a))), implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a))))), true, ifeq(is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a))), implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a))))), true), true, ifeq(is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by lemma 12 } 11.65/11.82 ifeq(ifeq(ifeq(is_a_theorem(implies(implies(implies(implies(implies(b, not(not(b))), implies(not(b), a)), implies(not(b), a)), implies(implies(not(a), b), implies(not(b), a))), implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a))))), true, is_a_theorem(implies(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a))), implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a))))), true), true, ifeq(is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by lemma 13 } 11.65/11.82 ifeq(ifeq(true, true, ifeq(is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(ifeq(is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 3 (condensed_detachment) } 11.65/11.82 ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(implies(implies(not(a), not(not(b))), implies(not(b), a)), implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a))))), true, ifeq(is_a_theorem(implies(implies(not(a), not(not(b))), implies(not(b), a))), true, is_a_theorem(implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(ifeq(ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(implies(implies(not(a), not(not(b))), implies(not(b), a)), implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a))))), true), true, ifeq(is_a_theorem(implies(implies(not(a), not(not(b))), implies(not(b), a))), true, is_a_theorem(implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by lemma 8 } 11.65/11.82 ifeq(ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(implies(implies(implies(implies(not(a), not(not(b))), implies(not(b), a)), implies(implies(b, not(not(b))), implies(not(b), a))), implies(implies(b, not(not(b))), implies(not(b), a))), implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a))))), true, is_a_theorem(implies(implies(implies(not(a), not(not(b))), implies(not(b), a)), implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a))))), true), true, ifeq(is_a_theorem(implies(implies(not(a), not(not(b))), implies(not(b), a))), true, is_a_theorem(implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(ifeq(ifeq(ifeq(ifeq(true, true, ifeq(is_a_theorem(implies(implies(implies(implies(implies(not(a), not(not(b))), implies(not(b), a)), implies(implies(b, not(not(b))), implies(not(b), a))), implies(implies(b, not(not(b))), implies(not(b), a))), implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a))))), true, is_a_theorem(implies(implies(implies(not(a), not(not(b))), implies(not(b), a)), implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a))))), true), true), true, ifeq(is_a_theorem(implies(implies(not(a), not(not(b))), implies(not(b), a))), true, is_a_theorem(implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by lemma 12 } 11.65/11.82 ifeq(ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(implies(implies(implies(implies(implies(not(a), not(not(b))), implies(not(b), a)), implies(implies(b, not(not(b))), implies(not(b), a))), implies(implies(b, not(not(b))), implies(not(b), a))), implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a)))), implies(implies(implies(not(a), not(not(b))), implies(not(b), a)), implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a)))))), true, ifeq(is_a_theorem(implies(implies(implies(implies(implies(not(a), not(not(b))), implies(not(b), a)), implies(implies(b, not(not(b))), implies(not(b), a))), implies(implies(b, not(not(b))), implies(not(b), a))), implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a))))), true, is_a_theorem(implies(implies(implies(not(a), not(not(b))), implies(not(b), a)), implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a))))), true), true), true, ifeq(is_a_theorem(implies(implies(not(a), not(not(b))), implies(not(b), a))), true, is_a_theorem(implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 3 (condensed_detachment) } 11.65/11.82 ifeq(ifeq(ifeq(ifeq(true, true, ifeq(is_a_theorem(implies(implies(not(a), not(not(b))), implies(not(b), a))), true, is_a_theorem(implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 5 (mv_5) } 11.65/11.82 ifeq(ifeq(ifeq(ifeq(true, true, ifeq(true, true, is_a_theorem(implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(ifeq(ifeq(is_a_theorem(implies(implies(implies(b, not(not(b))), implies(not(a), not(not(b)))), implies(implies(b, not(not(b))), implies(not(b), a)))), true, is_a_theorem(implies(implies(not(a), b), implies(implies(b, not(not(b))), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by lemma 13 } 11.65/11.82 ifeq(ifeq(true, true, is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(true, true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 3 (condensed_detachment) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(is_a_theorem(implies(implies(not(not(not(b))), not(b)), implies(b, not(not(b))))), true, ifeq(is_a_theorem(implies(not(not(not(b))), not(b))), true, is_a_theorem(implies(b, not(not(b)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 5 (mv_5) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(true, true, ifeq(is_a_theorem(implies(not(not(not(b))), not(b))), true, is_a_theorem(implies(b, not(not(b)))), true), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(is_a_theorem(implies(not(not(not(b))), not(b))), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 3 (condensed_detachment) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(implies(implies(implies(?, ?), not(b)), not(b)), implies(implies(not(not(b)), not(implies(?, ?))), not(b)))), true, ifeq(is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(implies(implies(implies(?, ?), not(b)), not(b)), implies(implies(not(not(b)), not(implies(?, ?))), not(b)))), true), true, ifeq(is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 5 (mv_5) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), implies(implies(?, ?), not(b)))), true, is_a_theorem(implies(implies(implies(implies(?, ?), not(b)), not(b)), implies(implies(not(not(b)), not(implies(?, ?))), not(b)))), true), true, ifeq(is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by lemma 7 } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(true, true, ifeq(is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by lemma 10 } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(implies(implies(?, implies(?, ?)), ?), ?)), true, is_a_theorem(implies(?, ?)), true), true, is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(implies(implies(?, implies(?, ?)), ?), ?)), true), true, is_a_theorem(implies(?, ?)), true), true, is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by lemma 11 } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(implies(?, implies(?, ?)), implies(implies(implies(?, implies(?, ?)), ?), ?))), true, is_a_theorem(implies(implies(implies(?, implies(?, ?)), ?), ?)), true), true, is_a_theorem(implies(?, ?)), true), true, is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by lemma 9 } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(?, ?)), true), true, is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.82 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(?, ?)), true, is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.82 = { by axiom 1 (ifeq_axiom) } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(true, true, ifeq(is_a_theorem(implies(?, ?)), true, is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true), true), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by lemma 11 } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(implies(?, ?), implies(implies(implies(?, ?), not(b)), not(b)))), true, ifeq(is_a_theorem(implies(?, ?)), true, is_a_theorem(implies(implies(implies(?, ?), not(b)), not(b))), true), true), true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by axiom 3 (condensed_detachment) } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by axiom 1 (ifeq_axiom) } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by axiom 1 (ifeq_axiom) } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(true, true, ifeq(is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by lemma 7 } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(not(not(not(b))), implies(not(not(b)), not(implies(?, ?))))), true, is_a_theorem(implies(implies(implies(not(not(b)), not(implies(?, ?))), not(b)), implies(not(not(not(b))), not(b)))), true), true, ifeq(is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by axiom 1 (ifeq_axiom) } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(not(not(not(b))), implies(not(not(b)), not(implies(?, ?))))), true), true, is_a_theorem(implies(implies(implies(not(not(b)), not(implies(?, ?))), not(b)), implies(not(not(not(b))), not(b)))), true), true, ifeq(is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by axiom 5 (mv_5) } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(ifeq(is_a_theorem(implies(implies(not(not(implies(?, ?))), not(not(not(b)))), implies(not(not(b)), not(implies(?, ?))))), true, is_a_theorem(implies(not(not(not(b))), implies(not(not(b)), not(implies(?, ?))))), true), true, is_a_theorem(implies(implies(implies(not(not(b)), not(implies(?, ?))), not(b)), implies(not(not(not(b))), not(b)))), true), true, ifeq(is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by lemma 10 } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(ifeq(true, true, is_a_theorem(implies(implies(implies(not(not(b)), not(implies(?, ?))), not(b)), implies(not(not(not(b))), not(b)))), true), true, ifeq(is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by axiom 1 (ifeq_axiom) } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(ifeq(is_a_theorem(implies(implies(implies(not(not(b)), not(implies(?, ?))), not(b)), implies(not(not(not(b))), not(b)))), true, ifeq(is_a_theorem(implies(implies(not(not(b)), not(implies(?, ?))), not(b))), true, is_a_theorem(implies(not(not(not(b))), not(b))), true), true), true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by axiom 3 (condensed_detachment) } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(ifeq(true, true, is_a_theorem(implies(b, not(not(b)))), true), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by axiom 1 (ifeq_axiom) } 11.65/11.83 ifeq(is_a_theorem(implies(implies(b, not(not(b))), implies(implies(not(a), b), implies(not(b), a)))), true, ifeq(is_a_theorem(implies(b, not(not(b)))), true, is_a_theorem(implies(implies(not(a), b), implies(not(b), a))), true), true) 11.65/11.83 = { by axiom 3 (condensed_detachment) } 11.65/11.83 true 11.65/11.83 % SZS output end Proof 11.65/11.83 11.65/11.83 RESULT: Unsatisfiable (the axioms are contradictory). 11.65/11.83 EOF