TSTP Solution File: LCL171-3 by Twee---2.4.2
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% File : Twee---2.4.2
% Problem : LCL171-3 : TPTP v8.1.2. Released v2.3.0.
% Transfm : none
% Format : tptp:raw
% Command : parallel-twee %s --tstp --conditional-encoding if --smaller --drop-non-horn --give-up-on-saturation --explain-encoding --formal-proof
% Computer : n032.cluster.edu
% Model : x86_64 x86_64
% CPU : Intel(R) Xeon(R) CPU E5-2620 v4 2.10GHz
% Memory : 8042.1875MB
% OS : Linux 3.10.0-693.el7.x86_64
% CPULimit : 300s
% WCLimit : 300s
% DateTime : Thu Aug 31 08:17:45 EDT 2023
% Result : Unsatisfiable 0.16s 0.34s
% Output : Proof 0.16s
% Verified :
% SZS Type : -
% Comments :
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%----WARNING: Could not form TPTP format derivation
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%----ORIGINAL SYSTEM OUTPUT
% 0.00/0.10 % Problem : LCL171-3 : TPTP v8.1.2. Released v2.3.0.
% 0.00/0.11 % Command : parallel-twee %s --tstp --conditional-encoding if --smaller --drop-non-horn --give-up-on-saturation --explain-encoding --formal-proof
% 0.11/0.31 % Computer : n032.cluster.edu
% 0.11/0.31 % Model : x86_64 x86_64
% 0.11/0.31 % CPU : Intel(R) Xeon(R) CPU E5-2620 v4 @ 2.10GHz
% 0.11/0.31 % Memory : 8042.1875MB
% 0.11/0.31 % OS : Linux 3.10.0-693.el7.x86_64
% 0.11/0.31 % CPULimit : 300
% 0.11/0.31 % WCLimit : 300
% 0.11/0.31 % DateTime : Fri Aug 25 07:18:27 EDT 2023
% 0.11/0.31 % CPUTime :
% 0.16/0.34 Command-line arguments: --flatten
% 0.16/0.34
% 0.16/0.34 % SZS status Unsatisfiable
% 0.16/0.34
% 0.16/0.34 % SZS output start Proof
% 0.16/0.34 Take the following subset of the input axioms:
% 0.16/0.34 fof(axiom_1_4, axiom, ![A, B]: axiom(implies(or(A, B), or(B, A)))).
% 0.16/0.34 fof(implies_definition, axiom, ![X, Y]: implies(X, Y)=or(not(X), Y)).
% 0.16/0.34 fof(prove_this, negated_conjecture, ~theorem(implies(implies(p, not(q)), implies(q, not(p))))).
% 0.16/0.34 fof(rule_1, axiom, ![X2]: (theorem(X2) | ~axiom(X2))).
% 0.16/0.34
% 0.16/0.34 Now clausify the problem and encode Horn clauses using encoding 3 of
% 0.16/0.34 http://www.cse.chalmers.se/~nicsma/papers/horn.pdf.
% 0.16/0.34 We repeatedly replace C & s=t => u=v by the two clauses:
% 0.16/0.35 fresh(y, y, x1...xn) = u
% 0.16/0.35 C => fresh(s, t, x1...xn) = v
% 0.16/0.35 where fresh is a fresh function symbol and x1..xn are the free
% 0.16/0.35 variables of u and v.
% 0.16/0.35 A predicate p(X) is encoded as p(X)=true (this is sound, because the
% 0.16/0.35 input problem has no model of domain size 1).
% 0.16/0.35
% 0.16/0.35 The encoding turns the above axioms into the following unit equations and goals:
% 0.16/0.35
% 0.16/0.35 Axiom 1 (rule_1): fresh2(X, X, Y) = true.
% 0.16/0.35 Axiom 2 (implies_definition): implies(X, Y) = or(not(X), Y).
% 0.16/0.35 Axiom 3 (rule_1): fresh2(axiom(X), true, X) = theorem(X).
% 0.16/0.35 Axiom 4 (axiom_1_4): axiom(implies(or(X, Y), or(Y, X))) = true.
% 0.16/0.35
% 0.16/0.35 Goal 1 (prove_this): theorem(implies(implies(p, not(q)), implies(q, not(p)))) = true.
% 0.16/0.35 Proof:
% 0.16/0.35 theorem(implies(implies(p, not(q)), implies(q, not(p))))
% 0.16/0.35 = { by axiom 3 (rule_1) R->L }
% 0.16/0.35 fresh2(axiom(implies(implies(p, not(q)), implies(q, not(p)))), true, implies(implies(p, not(q)), implies(q, not(p))))
% 0.16/0.35 = { by axiom 2 (implies_definition) }
% 0.16/0.35 fresh2(axiom(implies(or(not(p), not(q)), implies(q, not(p)))), true, implies(implies(p, not(q)), implies(q, not(p))))
% 0.16/0.35 = { by axiom 2 (implies_definition) }
% 0.16/0.35 fresh2(axiom(implies(or(not(p), not(q)), or(not(q), not(p)))), true, implies(implies(p, not(q)), implies(q, not(p))))
% 0.16/0.35 = { by axiom 4 (axiom_1_4) }
% 0.16/0.35 fresh2(true, true, implies(implies(p, not(q)), implies(q, not(p))))
% 0.16/0.35 = { by axiom 1 (rule_1) }
% 0.16/0.35 true
% 0.16/0.35 % SZS output end Proof
% 0.16/0.35
% 0.16/0.35 RESULT: Unsatisfiable (the axioms are contradictory).
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