TSTP Solution File: SET080-6 by Twee---2.4.2
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% File : Twee---2.4.2
% Problem : SET080-6 : TPTP v8.1.2. Bugfixed v2.1.0.
% 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 : n001.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 15:31:07 EDT 2023
% Result : Unsatisfiable 0.19s 0.53s
% Output : Proof 0.19s
% Verified :
% SZS Type : -
% Comments :
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%----WARNING: Could not form TPTP format derivation
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%----ORIGINAL SYSTEM OUTPUT
% 0.00/0.12 % Problem : SET080-6 : TPTP v8.1.2. Bugfixed v2.1.0.
% 0.00/0.13 % Command : parallel-twee %s --tstp --conditional-encoding if --smaller --drop-non-horn --give-up-on-saturation --explain-encoding --formal-proof
% 0.13/0.34 % Computer : n001.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 : 300
% 0.13/0.34 % WCLimit : 300
% 0.13/0.34 % DateTime : Sat Aug 26 12:36:30 EDT 2023
% 0.13/0.34 % CPUTime :
% 0.19/0.53 Command-line arguments: --no-flatten-goal
% 0.19/0.53
% 0.19/0.53 % SZS status Unsatisfiable
% 0.19/0.53
% 0.19/0.53 % SZS output start Proof
% 0.19/0.53 Take the following subset of the input axioms:
% 0.19/0.53 fof(class_elements_are_sets, axiom, ![X]: subclass(X, universal_class)).
% 0.19/0.53 fof(inductive1, axiom, ![X2]: (~inductive(X2) | member(null_class, X2))).
% 0.19/0.53 fof(omega_is_inductive1, axiom, inductive(omega)).
% 0.19/0.53 fof(prove_null_class_in_its_singleton_1, negated_conjecture, ~member(null_class, singleton(null_class))).
% 0.19/0.53 fof(singleton_set, axiom, ![X2]: unordered_pair(X2, X2)=singleton(X2)).
% 0.19/0.53 fof(subclass_members, axiom, ![Y, U, X2]: (~subclass(X2, Y) | (~member(U, X2) | member(U, Y)))).
% 0.19/0.53 fof(unordered_pair2, axiom, ![X2, Y2]: (~member(X2, universal_class) | member(X2, unordered_pair(X2, Y2)))).
% 0.19/0.53
% 0.19/0.53 Now clausify the problem and encode Horn clauses using encoding 3 of
% 0.19/0.53 http://www.cse.chalmers.se/~nicsma/papers/horn.pdf.
% 0.19/0.53 We repeatedly replace C & s=t => u=v by the two clauses:
% 0.19/0.53 fresh(y, y, x1...xn) = u
% 0.19/0.53 C => fresh(s, t, x1...xn) = v
% 0.19/0.53 where fresh is a fresh function symbol and x1..xn are the free
% 0.19/0.53 variables of u and v.
% 0.19/0.53 A predicate p(X) is encoded as p(X)=true (this is sound, because the
% 0.19/0.53 input problem has no model of domain size 1).
% 0.19/0.53
% 0.19/0.53 The encoding turns the above axioms into the following unit equations and goals:
% 0.19/0.53
% 0.19/0.53 Axiom 1 (omega_is_inductive1): inductive(omega) = true2.
% 0.19/0.53 Axiom 2 (singleton_set): unordered_pair(X, X) = singleton(X).
% 0.19/0.53 Axiom 3 (class_elements_are_sets): subclass(X, universal_class) = true2.
% 0.19/0.53 Axiom 4 (inductive1): fresh37(X, X, Y) = true2.
% 0.19/0.53 Axiom 5 (inductive1): fresh37(inductive(X), true2, X) = member(null_class, X).
% 0.19/0.53 Axiom 6 (subclass_members): fresh10(X, X, Y, Z) = true2.
% 0.19/0.53 Axiom 7 (unordered_pair2): fresh6(X, X, Y, Z) = true2.
% 0.19/0.53 Axiom 8 (subclass_members): fresh11(X, X, Y, Z, W) = member(W, Z).
% 0.19/0.53 Axiom 9 (unordered_pair2): fresh6(member(X, universal_class), true2, X, Y) = member(X, unordered_pair(X, Y)).
% 0.19/0.53 Axiom 10 (subclass_members): fresh11(member(X, Y), true2, Y, Z, X) = fresh10(subclass(Y, Z), true2, Z, X).
% 0.19/0.53
% 0.19/0.53 Goal 1 (prove_null_class_in_its_singleton_1): member(null_class, singleton(null_class)) = true2.
% 0.19/0.53 Proof:
% 0.19/0.53 member(null_class, singleton(null_class))
% 0.19/0.53 = { by axiom 2 (singleton_set) R->L }
% 0.19/0.53 member(null_class, unordered_pair(null_class, null_class))
% 0.19/0.53 = { by axiom 9 (unordered_pair2) R->L }
% 0.19/0.53 fresh6(member(null_class, universal_class), true2, null_class, null_class)
% 0.19/0.53 = { by axiom 8 (subclass_members) R->L }
% 0.19/0.53 fresh6(fresh11(true2, true2, omega, universal_class, null_class), true2, null_class, null_class)
% 0.19/0.53 = { by axiom 4 (inductive1) R->L }
% 0.19/0.53 fresh6(fresh11(fresh37(true2, true2, omega), true2, omega, universal_class, null_class), true2, null_class, null_class)
% 0.19/0.53 = { by axiom 1 (omega_is_inductive1) R->L }
% 0.19/0.53 fresh6(fresh11(fresh37(inductive(omega), true2, omega), true2, omega, universal_class, null_class), true2, null_class, null_class)
% 0.19/0.53 = { by axiom 5 (inductive1) }
% 0.19/0.53 fresh6(fresh11(member(null_class, omega), true2, omega, universal_class, null_class), true2, null_class, null_class)
% 0.19/0.53 = { by axiom 10 (subclass_members) }
% 0.19/0.53 fresh6(fresh10(subclass(omega, universal_class), true2, universal_class, null_class), true2, null_class, null_class)
% 0.19/0.53 = { by axiom 3 (class_elements_are_sets) }
% 0.19/0.53 fresh6(fresh10(true2, true2, universal_class, null_class), true2, null_class, null_class)
% 0.19/0.53 = { by axiom 6 (subclass_members) }
% 0.19/0.53 fresh6(true2, true2, null_class, null_class)
% 0.19/0.53 = { by axiom 7 (unordered_pair2) }
% 0.19/0.53 true2
% 0.19/0.53 % SZS output end Proof
% 0.19/0.53
% 0.19/0.53 RESULT: Unsatisfiable (the axioms are contradictory).
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