0.04/0.13 % Problem : theBenchmark.p : TPTP v0.0.0. Released v0.0.0. 0.13/0.14 % Command : twee %s --tstp --casc --quiet --explain-encoding --conditional-encoding if --smaller --drop-non-horn 0.13/0.35 % Computer : n026.cluster.edu 0.13/0.35 % Model : x86_64 x86_64 0.13/0.35 % CPU : Intel(R) Xeon(R) CPU E5-2620 v4 @ 2.10GHz 0.13/0.35 % Memory : 8042.1875MB 0.13/0.35 % OS : Linux 3.10.0-693.el7.x86_64 0.13/0.35 % CPULimit : 180 0.13/0.35 % DateTime : Thu Aug 29 13:25:05 EDT 2019 0.20/0.35 % CPUTime : 2.84/3.01 % SZS status Unsatisfiable 2.84/3.01 2.84/3.02 % SZS output start Proof 2.84/3.02 Take the following subset of the input axioms: 2.88/3.05 fof(additive_inverse_additive_inverse, axiom, ![X]: X=additive_inverse(additive_inverse(X))). 2.88/3.05 fof(associativity_for_addition, axiom, ![X, Y, Z]: add(add(X, Y), Z)=add(X, add(Y, Z))). 2.88/3.05 fof(associator, axiom, ![X, Y, Z]: associator(X, Y, Z)=add(multiply(multiply(X, Y), Z), additive_inverse(multiply(X, multiply(Y, Z))))). 2.88/3.05 fof(commutativity_for_addition, axiom, ![X, Y]: add(Y, X)=add(X, Y)). 2.88/3.05 fof(distribute1, axiom, ![X, Y, Z]: add(multiply(X, Y), multiply(X, Z))=multiply(X, add(Y, Z))). 2.88/3.05 fof(distribute2, axiom, ![X, Y, Z]: multiply(add(X, Y), Z)=add(multiply(X, Z), multiply(Y, Z))). 2.88/3.05 fof(left_additive_identity, axiom, ![X]: add(additive_identity, X)=X). 2.88/3.05 fof(left_additive_inverse, axiom, ![X]: additive_identity=add(additive_inverse(X), X)). 2.88/3.05 fof(left_alternative, axiom, ![X, Y]: multiply(multiply(X, X), Y)=multiply(X, multiply(X, Y))). 2.88/3.05 fof(left_multiplicative_zero, axiom, ![X]: multiply(additive_identity, X)=additive_identity). 2.88/3.05 fof(prove_flexible_law, negated_conjecture, associator(x, y, x)!=additive_identity). 2.88/3.05 fof(right_additive_identity, axiom, ![X]: add(X, additive_identity)=X). 2.88/3.05 fof(right_alternative, axiom, ![X, Y]: multiply(X, multiply(Y, Y))=multiply(multiply(X, Y), Y)). 2.88/3.05 fof(right_multiplicative_zero, axiom, ![X]: multiply(X, additive_identity)=additive_identity). 2.88/3.05 2.88/3.05 Now clausify the problem and encode Horn clauses using encoding 3 of 2.88/3.05 http://www.cse.chalmers.se/~nicsma/papers/horn.pdf. 2.88/3.05 We repeatedly replace C & s=t => u=v by the two clauses: 2.88/3.05 fresh(y, y, x1...xn) = u 2.88/3.05 C => fresh(s, t, x1...xn) = v 2.88/3.05 where fresh is a fresh function symbol and x1..xn are the free 2.88/3.05 variables of u and v. 2.88/3.05 A predicate p(X) is encoded as p(X)=true (this is sound, because the 2.88/3.05 input problem has no model of domain size 1). 2.88/3.05 2.88/3.05 The encoding turns the above axioms into the following unit equations and goals: 2.88/3.05 2.88/3.05 Axiom 1 (right_alternative): multiply(X, multiply(Y, Y)) = multiply(multiply(X, Y), Y). 2.88/3.05 Axiom 2 (commutativity_for_addition): add(X, Y) = add(Y, X). 2.88/3.05 Axiom 3 (left_alternative): multiply(multiply(X, X), Y) = multiply(X, multiply(X, Y)). 2.88/3.05 Axiom 4 (distribute2): multiply(add(X, Y), Z) = add(multiply(X, Z), multiply(Y, Z)). 2.88/3.05 Axiom 5 (left_multiplicative_zero): multiply(additive_identity, X) = additive_identity. 2.88/3.05 Axiom 6 (left_additive_inverse): additive_identity = add(additive_inverse(X), X). 2.88/3.05 Axiom 7 (left_additive_identity): add(additive_identity, X) = X. 2.88/3.05 Axiom 8 (right_multiplicative_zero): multiply(X, additive_identity) = additive_identity. 2.88/3.05 Axiom 9 (additive_inverse_additive_inverse): X = additive_inverse(additive_inverse(X)). 2.88/3.05 Axiom 10 (associativity_for_addition): add(add(X, Y), Z) = add(X, add(Y, Z)). 2.88/3.05 Axiom 11 (associator): associator(X, Y, Z) = add(multiply(multiply(X, Y), Z), additive_inverse(multiply(X, multiply(Y, Z)))). 2.88/3.05 Axiom 12 (distribute1): add(multiply(X, Y), multiply(X, Z)) = multiply(X, add(Y, Z)). 2.88/3.05 Axiom 13 (right_additive_identity): add(X, additive_identity) = X. 2.88/3.05 2.88/3.05 Lemma 14: add(X, additive_inverse(X)) = additive_identity. 2.88/3.05 Proof: 2.88/3.05 add(X, additive_inverse(X)) 2.88/3.05 = { by axiom 2 (commutativity_for_addition) } 2.88/3.05 add(additive_inverse(X), X) 2.88/3.05 = { by axiom 6 (left_additive_inverse) } 2.88/3.05 additive_identity 2.88/3.05 2.88/3.05 Lemma 15: add(X, add(Y, additive_inverse(X))) = Y. 2.88/3.05 Proof: 2.88/3.05 add(X, add(Y, additive_inverse(X))) 2.88/3.05 = { by axiom 2 (commutativity_for_addition) } 2.88/3.05 add(X, add(additive_inverse(X), Y)) 2.88/3.05 = { by axiom 10 (associativity_for_addition) } 2.88/3.05 add(add(X, additive_inverse(X)), Y) 2.88/3.05 = { by lemma 14 } 2.88/3.05 add(additive_identity, Y) 2.88/3.05 = { by axiom 7 (left_additive_identity) } 2.88/3.05 Y 2.88/3.05 2.88/3.05 Lemma 16: add(additive_inverse(multiply(X, Y)), multiply(add(X, Z), Y)) = multiply(Z, Y). 2.88/3.05 Proof: 2.88/3.05 add(additive_inverse(multiply(X, Y)), multiply(add(X, Z), Y)) 2.88/3.05 = { by axiom 2 (commutativity_for_addition) } 2.88/3.05 add(additive_inverse(multiply(X, Y)), multiply(add(Z, X), Y)) 2.88/3.05 = { by axiom 2 (commutativity_for_addition) } 2.88/3.05 add(multiply(add(Z, X), Y), additive_inverse(multiply(X, Y))) 2.88/3.05 = { by axiom 4 (distribute2) } 2.88/3.05 add(add(multiply(Z, Y), multiply(X, Y)), additive_inverse(multiply(X, Y))) 2.88/3.05 = { by axiom 10 (associativity_for_addition) } 2.88/3.05 add(multiply(Z, Y), add(multiply(X, Y), additive_inverse(multiply(X, Y)))) 2.88/3.05 = { by lemma 14 } 2.88/3.05 add(multiply(Z, Y), additive_identity) 2.88/3.05 = { by axiom 13 (right_additive_identity) } 2.88/3.05 multiply(Z, Y) 2.88/3.05 2.88/3.05 Lemma 17: additive_inverse(multiply(X, Y)) = multiply(additive_inverse(X), Y). 2.88/3.05 Proof: 2.88/3.05 additive_inverse(multiply(X, Y)) 2.88/3.05 = { by axiom 13 (right_additive_identity) } 2.88/3.05 add(additive_inverse(multiply(X, Y)), additive_identity) 2.88/3.05 = { by axiom 5 (left_multiplicative_zero) } 2.88/3.05 add(additive_inverse(multiply(X, Y)), multiply(additive_identity, Y)) 2.88/3.05 = { by lemma 14 } 2.88/3.05 add(additive_inverse(multiply(X, Y)), multiply(add(X, additive_inverse(X)), Y)) 2.88/3.05 = { by lemma 16 } 2.88/3.05 multiply(additive_inverse(X), Y) 2.88/3.05 2.88/3.05 Lemma 18: multiply(additive_inverse(X), Y) = multiply(X, additive_inverse(Y)). 2.88/3.05 Proof: 2.88/3.05 multiply(additive_inverse(X), Y) 2.88/3.05 = { by axiom 13 (right_additive_identity) } 2.88/3.05 add(multiply(additive_inverse(X), Y), additive_identity) 2.88/3.05 = { by lemma 17 } 2.88/3.05 add(additive_inverse(multiply(X, Y)), additive_identity) 2.88/3.05 = { by axiom 8 (right_multiplicative_zero) } 2.88/3.05 add(additive_inverse(multiply(X, Y)), multiply(X, additive_identity)) 2.88/3.05 = { by lemma 14 } 2.88/3.05 add(additive_inverse(multiply(X, Y)), multiply(X, add(Y, additive_inverse(Y)))) 2.88/3.05 = { by axiom 2 (commutativity_for_addition) } 2.88/3.05 add(additive_inverse(multiply(X, Y)), multiply(X, add(additive_inverse(Y), Y))) 2.88/3.05 = { by axiom 2 (commutativity_for_addition) } 2.88/3.05 add(multiply(X, add(additive_inverse(Y), Y)), additive_inverse(multiply(X, Y))) 2.88/3.05 = { by axiom 12 (distribute1) } 2.88/3.05 add(add(multiply(X, additive_inverse(Y)), multiply(X, Y)), additive_inverse(multiply(X, Y))) 2.88/3.05 = { by axiom 10 (associativity_for_addition) } 2.88/3.05 add(multiply(X, additive_inverse(Y)), add(multiply(X, Y), additive_inverse(multiply(X, Y)))) 2.88/3.05 = { by lemma 14 } 2.88/3.05 add(multiply(X, additive_inverse(Y)), additive_identity) 2.88/3.05 = { by axiom 13 (right_additive_identity) } 2.88/3.05 multiply(X, additive_inverse(Y)) 2.88/3.05 2.88/3.05 Lemma 19: additive_inverse(multiply(X, Y)) = multiply(X, additive_inverse(Y)). 2.88/3.05 Proof: 2.88/3.05 additive_inverse(multiply(X, Y)) 2.88/3.05 = { by axiom 13 (right_additive_identity) } 2.88/3.05 add(additive_inverse(multiply(X, Y)), additive_identity) 2.88/3.05 = { by axiom 5 (left_multiplicative_zero) } 2.88/3.05 add(additive_inverse(multiply(X, Y)), multiply(additive_identity, Y)) 2.88/3.05 = { by lemma 14 } 2.88/3.05 add(additive_inverse(multiply(X, Y)), multiply(add(X, additive_inverse(X)), Y)) 2.88/3.05 = { by lemma 16 } 2.88/3.05 multiply(additive_inverse(X), Y) 2.88/3.05 = { by lemma 18 } 2.88/3.09 multiply(X, additive_inverse(Y)) 2.88/3.09 2.88/3.09 Goal 1 (prove_flexible_law): associator(x, y, x) = additive_identity. 2.88/3.09 Proof: 2.88/3.09 associator(x, y, x) 2.88/3.09 = { by lemma 15 } 2.88/3.09 associator(x, add(x, add(y, additive_inverse(x))), x) 2.88/3.09 = { by axiom 11 (associator) } 2.88/3.09 add(multiply(multiply(x, add(x, add(y, additive_inverse(x)))), x), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 13 (right_additive_identity) } 2.88/3.09 add(multiply(multiply(x, add(x, add(y, additive_inverse(x)))), add(x, additive_identity)), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by lemma 14 } 2.88/3.09 add(multiply(multiply(x, add(x, add(y, additive_inverse(x)))), add(x, add(add(y, additive_inverse(x)), additive_inverse(add(y, additive_inverse(x)))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 10 (associativity_for_addition) } 2.88/3.09 add(multiply(multiply(x, add(x, add(y, additive_inverse(x)))), add(add(x, add(y, additive_inverse(x))), additive_inverse(add(y, additive_inverse(x))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 12 (distribute1) } 2.88/3.09 add(add(multiply(multiply(x, add(x, add(y, additive_inverse(x)))), add(x, add(y, additive_inverse(x)))), multiply(multiply(x, add(x, add(y, additive_inverse(x)))), additive_inverse(add(y, additive_inverse(x))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 1 (right_alternative) } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), multiply(multiply(x, add(x, add(y, additive_inverse(x)))), additive_inverse(add(y, additive_inverse(x))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by lemma 19 } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), additive_inverse(multiply(multiply(x, add(x, add(y, additive_inverse(x)))), add(y, additive_inverse(x))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 12 (distribute1) } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), additive_inverse(multiply(add(multiply(x, x), multiply(x, add(y, additive_inverse(x)))), add(y, additive_inverse(x))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 2 (commutativity_for_addition) } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), additive_inverse(multiply(add(multiply(x, add(y, additive_inverse(x))), multiply(x, x)), add(y, additive_inverse(x))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 4 (distribute2) } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), additive_inverse(add(multiply(multiply(x, add(y, additive_inverse(x))), add(y, additive_inverse(x))), multiply(multiply(x, x), add(y, additive_inverse(x)))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 1 (right_alternative) } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), additive_inverse(add(multiply(x, multiply(add(y, additive_inverse(x)), add(y, additive_inverse(x)))), multiply(multiply(x, x), add(y, additive_inverse(x)))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 3 (left_alternative) } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), additive_inverse(add(multiply(x, multiply(add(y, additive_inverse(x)), add(y, additive_inverse(x)))), multiply(x, multiply(x, add(y, additive_inverse(x))))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 12 (distribute1) } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), additive_inverse(multiply(x, add(multiply(add(y, additive_inverse(x)), add(y, additive_inverse(x))), multiply(x, add(y, additive_inverse(x))))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 4 (distribute2) } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), additive_inverse(multiply(x, multiply(add(add(y, additive_inverse(x)), x), add(y, additive_inverse(x)))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 2 (commutativity_for_addition) } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(y, additive_inverse(x)))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by lemma 19 } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), multiply(x, additive_inverse(multiply(add(x, add(y, additive_inverse(x))), add(y, additive_inverse(x)))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by lemma 19 } 2.88/3.09 add(add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x))))), multiply(x, multiply(add(x, add(y, additive_inverse(x))), additive_inverse(add(y, additive_inverse(x)))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 12 (distribute1) } 2.88/3.09 add(multiply(x, add(multiply(add(x, add(y, additive_inverse(x))), add(x, add(y, additive_inverse(x)))), multiply(add(x, add(y, additive_inverse(x))), additive_inverse(add(y, additive_inverse(x)))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 12 (distribute1) } 2.88/3.09 add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(add(x, add(y, additive_inverse(x))), additive_inverse(add(y, additive_inverse(x)))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 10 (associativity_for_addition) } 2.88/3.09 add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, add(add(y, additive_inverse(x)), additive_inverse(add(y, additive_inverse(x))))))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by lemma 14 } 2.88/3.09 add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), add(x, additive_identity))), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by axiom 13 (right_additive_identity) } 2.88/3.09 add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)), additive_inverse(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by lemma 17 } 2.88/3.09 add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)), multiply(additive_inverse(x), multiply(add(x, add(y, additive_inverse(x))), x))) 2.88/3.09 = { by lemma 18 } 2.88/3.09 add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)), multiply(x, additive_inverse(multiply(add(x, add(y, additive_inverse(x))), x)))) 2.88/3.09 = { by lemma 17 } 2.88/3.09 add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)), multiply(x, multiply(additive_inverse(add(x, add(y, additive_inverse(x)))), x))) 2.88/3.09 = { by lemma 18 } 2.88/3.09 add(multiply(x, multiply(add(x, add(y, additive_inverse(x))), x)), multiply(x, multiply(add(x, add(y, additive_inverse(x))), additive_inverse(x)))) 2.88/3.09 = { by axiom 12 (distribute1) } 2.88/3.09 multiply(x, add(multiply(add(x, add(y, additive_inverse(x))), x), multiply(add(x, add(y, additive_inverse(x))), additive_inverse(x)))) 2.88/3.09 = { by lemma 18 } 2.88/3.09 multiply(x, add(multiply(add(x, add(y, additive_inverse(x))), x), multiply(additive_inverse(add(x, add(y, additive_inverse(x)))), x))) 2.88/3.09 = { by axiom 4 (distribute2) } 2.88/3.09 multiply(x, multiply(add(add(x, add(y, additive_inverse(x))), additive_inverse(add(x, add(y, additive_inverse(x))))), x)) 2.88/3.09 = { by axiom 10 (associativity_for_addition) } 2.88/3.09 multiply(x, multiply(add(x, add(add(y, additive_inverse(x)), additive_inverse(add(x, add(y, additive_inverse(x)))))), x)) 2.88/3.09 = { by axiom 2 (commutativity_for_addition) } 2.88/3.09 multiply(x, multiply(add(x, add(add(y, additive_inverse(x)), additive_inverse(add(add(y, additive_inverse(x)), x)))), x)) 2.88/3.09 = { by axiom 2 (commutativity_for_addition) } 2.88/3.09 multiply(x, multiply(add(x, add(additive_inverse(add(add(y, additive_inverse(x)), x)), add(y, additive_inverse(x)))), x)) 2.88/3.09 = { by axiom 10 (associativity_for_addition) } 2.88/3.09 multiply(x, multiply(add(add(x, additive_inverse(add(add(y, additive_inverse(x)), x))), add(y, additive_inverse(x))), x)) 2.88/3.09 = { by axiom 2 (commutativity_for_addition) } 2.88/3.09 multiply(x, multiply(add(add(x, additive_inverse(add(x, add(y, additive_inverse(x))))), add(y, additive_inverse(x))), x)) 2.88/3.09 = { by axiom 9 (additive_inverse_additive_inverse) } 2.88/3.09 multiply(x, multiply(add(add(x, additive_inverse(add(x, additive_inverse(additive_inverse(add(y, additive_inverse(x))))))), add(y, additive_inverse(x))), x)) 2.88/3.09 = { by axiom 2 (commutativity_for_addition) } 2.88/3.09 multiply(x, multiply(add(add(x, additive_inverse(add(additive_inverse(additive_inverse(add(y, additive_inverse(x)))), x))), add(y, additive_inverse(x))), x)) 2.88/3.09 = { by lemma 15 } 2.88/3.09 multiply(x, multiply(add(add(additive_inverse(add(y, additive_inverse(x))), add(add(x, additive_inverse(add(additive_inverse(additive_inverse(add(y, additive_inverse(x)))), x))), additive_inverse(additive_inverse(add(y, additive_inverse(x)))))), add(y, additive_inverse(x))), x)) 2.88/3.09 = { by axiom 2 (commutativity_for_addition) } 2.88/3.09 multiply(x, multiply(add(add(additive_inverse(add(y, additive_inverse(x))), add(additive_inverse(additive_inverse(add(y, additive_inverse(x)))), add(x, additive_inverse(add(additive_inverse(additive_inverse(add(y, additive_inverse(x)))), x))))), add(y, additive_inverse(x))), x)) 2.88/3.09 = { by axiom 10 (associativity_for_addition) } 2.88/3.09 multiply(x, multiply(add(add(additive_inverse(add(y, additive_inverse(x))), add(add(additive_inverse(additive_inverse(add(y, additive_inverse(x)))), x), additive_inverse(add(additive_inverse(additive_inverse(add(y, additive_inverse(x)))), x)))), add(y, additive_inverse(x))), x)) 2.88/3.09 = { by lemma 14 } 2.88/3.09 multiply(x, multiply(add(add(additive_inverse(add(y, additive_inverse(x))), additive_identity), add(y, additive_inverse(x))), x)) 2.88/3.09 = { by axiom 13 (right_additive_identity) } 2.88/3.09 multiply(x, multiply(add(additive_inverse(add(y, additive_inverse(x))), add(y, additive_inverse(x))), x)) 2.88/3.09 = { by axiom 2 (commutativity_for_addition) } 2.88/3.09 multiply(x, multiply(add(add(y, additive_inverse(x)), additive_inverse(add(y, additive_inverse(x)))), x)) 2.88/3.09 = { by lemma 14 } 2.88/3.09 multiply(x, multiply(additive_identity, x)) 2.88/3.09 = { by axiom 5 (left_multiplicative_zero) } 2.88/3.09 multiply(x, additive_identity) 2.88/3.09 = { by axiom 8 (right_multiplicative_zero) } 2.88/3.09 additive_identity 2.88/3.09 % SZS output end Proof 2.88/3.09 2.88/3.09 RESULT: Unsatisfiable (the axioms are contradictory). 2.88/3.09 EOF