0.04/0.12 % Problem : theBenchmark.p : TPTP v0.0.0. Released v0.0.0. 0.04/0.12 % Command : twee %s --tstp --casc --quiet --explain-encoding --conditional-encoding if --smaller --drop-non-horn 0.12/0.33 % Computer : n018.cluster.edu 0.12/0.33 % Model : x86_64 x86_64 0.12/0.33 % CPU : Intel(R) Xeon(R) CPU E5-2620 v4 @ 2.10GHz 0.12/0.33 % Memory : 8042.1875MB 0.12/0.33 % OS : Linux 3.10.0-693.el7.x86_64 0.12/0.33 % CPULimit : 180 0.12/0.33 % DateTime : Thu Aug 29 10:40:51 EDT 2019 0.12/0.34 % CPUTime : 9.64/9.84 % SZS status Unsatisfiable 9.64/9.84 9.64/9.84 % SZS output start Proof 9.64/9.84 Take the following subset of the input axioms: 9.64/9.84 fof(b_definition, axiom, ![Y, X, Z]: apply(X, apply(Y, Z))=apply(apply(apply(b, X), Y), Z)). 9.64/9.84 fof(prove_strong_fixed_point, negated_conjecture, apply(strong_fixed_point, fixed_pt)!=apply(fixed_pt, apply(strong_fixed_point, fixed_pt))). 9.64/9.84 fof(strong_fixed_point, axiom, strong_fixed_point=apply(apply(b, apply(w1, w1)), apply(apply(b, apply(b, w1)), apply(apply(b, b), b)))). 9.64/9.84 fof(w1_definition, axiom, ![Y, X]: apply(apply(Y, X), X)=apply(apply(w1, X), Y)). 9.64/9.84 9.64/9.84 Now clausify the problem and encode Horn clauses using encoding 3 of 9.64/9.84 http://www.cse.chalmers.se/~nicsma/papers/horn.pdf. 9.64/9.84 We repeatedly replace C & s=t => u=v by the two clauses: 9.64/9.84 fresh(y, y, x1...xn) = u 9.64/9.84 C => fresh(s, t, x1...xn) = v 9.64/9.84 where fresh is a fresh function symbol and x1..xn are the free 9.64/9.84 variables of u and v. 9.64/9.84 A predicate p(X) is encoded as p(X)=true (this is sound, because the 9.64/9.84 input problem has no model of domain size 1). 9.64/9.84 9.64/9.84 The encoding turns the above axioms into the following unit equations and goals: 9.64/9.84 9.64/9.84 Axiom 1 (b_definition): apply(X, apply(Y, Z)) = apply(apply(apply(b, X), Y), Z). 9.64/9.84 Axiom 2 (w1_definition): apply(apply(X, Y), Y) = apply(apply(w1, Y), X). 9.64/9.84 Axiom 3 (strong_fixed_point): strong_fixed_point = apply(apply(b, apply(w1, w1)), apply(apply(b, apply(b, w1)), apply(apply(b, b), b))). 9.64/9.84 9.64/9.84 Lemma 4: apply(apply(w1, apply(apply(b, apply(b, X)), w1)), w1) = apply(strong_fixed_point, X). 9.64/9.84 Proof: 9.64/9.84 apply(apply(w1, apply(apply(b, apply(b, X)), w1)), w1) 9.64/9.84 = { by axiom 1 (b_definition) } 9.64/9.84 apply(apply(apply(apply(b, w1), apply(b, apply(b, X))), w1), w1) 9.64/9.84 = { by axiom 2 (w1_definition) } 9.64/9.84 apply(apply(w1, w1), apply(apply(b, w1), apply(b, apply(b, X)))) 9.64/9.84 = { by axiom 1 (b_definition) } 9.64/9.84 apply(apply(w1, w1), apply(apply(b, w1), apply(apply(apply(b, b), b), X))) 9.64/9.84 = { by axiom 1 (b_definition) } 9.64/9.84 apply(apply(w1, w1), apply(apply(apply(b, apply(b, w1)), apply(apply(b, b), b)), X)) 9.64/9.84 = { by axiom 1 (b_definition) } 9.64/9.84 apply(apply(apply(b, apply(w1, w1)), apply(apply(b, apply(b, w1)), apply(apply(b, b), b))), X) 9.64/9.84 = { by axiom 3 (strong_fixed_point) } 9.64/9.84 apply(strong_fixed_point, X) 9.64/9.84 9.64/9.84 Goal 1 (prove_strong_fixed_point): apply(strong_fixed_point, fixed_pt) = apply(fixed_pt, apply(strong_fixed_point, fixed_pt)). 9.64/9.84 Proof: 9.64/9.84 apply(strong_fixed_point, fixed_pt) 9.64/9.84 = { by lemma 4 } 9.64/9.84 apply(apply(w1, apply(apply(b, apply(b, fixed_pt)), w1)), w1) 9.64/9.84 = { by axiom 2 (w1_definition) } 9.64/9.84 apply(apply(w1, apply(apply(b, apply(b, fixed_pt)), w1)), apply(apply(b, apply(b, fixed_pt)), w1)) 9.64/9.84 = { by axiom 2 (w1_definition) } 9.64/9.84 apply(apply(apply(apply(b, apply(b, fixed_pt)), w1), apply(apply(b, apply(b, fixed_pt)), w1)), apply(apply(b, apply(b, fixed_pt)), w1)) 9.64/9.84 = { by axiom 1 (b_definition) } 9.64/9.84 apply(apply(apply(b, fixed_pt), apply(w1, apply(apply(b, apply(b, fixed_pt)), w1))), apply(apply(b, apply(b, fixed_pt)), w1)) 9.64/9.84 = { by axiom 1 (b_definition) } 9.64/9.84 apply(fixed_pt, apply(apply(w1, apply(apply(b, apply(b, fixed_pt)), w1)), apply(apply(b, apply(b, fixed_pt)), w1))) 9.64/9.84 = { by axiom 2 (w1_definition) } 9.64/9.84 apply(fixed_pt, apply(apply(w1, apply(apply(b, apply(b, fixed_pt)), w1)), w1)) 9.64/9.84 = { by lemma 4 } 9.64/9.84 apply(fixed_pt, apply(strong_fixed_point, fixed_pt)) 9.64/9.84 % SZS output end Proof 9.64/9.84 9.64/9.84 RESULT: Unsatisfiable (the axioms are contradictory). 9.64/9.84 EOF