TPTP Problem File: SWV021-1.p
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%--------------------------------------------------------------------------
% File : SWV021-1 : TPTP v9.0.0. Released v2.7.0.
% Domain : Software Verification
% Problem : Show that the add function is commutative.
% Version : [Cla03] axioms : Especial.
% English : A proof obligation formulated as a satisfiability problem.
% Given the definition of "add" on successor-naturals, show
% that no two terms t1 and t2 can be found such that
% add(t1,t2) /= add(t2,t1). In other words, show that adding
% the negation of that as a clause is still consistent.
% Refs : [Cla03] Claessen (2003), Email to G. Sutcliffe
% Source : [Cla03]
% Names :
% Status : Satisfiable
% Rating : 0.67 v9.0.0, 0.60 v8.2.0, 0.70 v8.1.0, 0.88 v7.5.0, 0.89 v7.4.0, 0.91 v7.3.0, 0.89 v7.1.0, 0.88 v7.0.0, 0.86 v6.3.0, 0.88 v6.2.0, 0.90 v6.1.0, 0.89 v6.0.0, 0.86 v5.5.0, 0.88 v5.4.0, 0.90 v5.3.0, 0.89 v5.2.0, 0.90 v5.0.0, 0.89 v4.1.0, 0.86 v4.0.1, 0.80 v4.0.0, 0.75 v3.7.0, 0.67 v3.5.0, 1.00 v3.4.0, 0.75 v3.3.0, 0.67 v3.2.0, 0.80 v3.1.0, 0.67 v2.7.0
% Syntax : Number of clauses : 5 ( 4 unt; 0 nHn; 2 RR)
% Number of literals : 6 ( 6 equ; 2 neg)
% Maximal clause size : 2 ( 1 avg)
% Maximal term depth : 3 ( 1 avg)
% Number of predicates : 1 ( 0 usr; 0 prp; 2-2 aty)
% Number of functors : 3 ( 3 usr; 1 con; 0-2 aty)
% Number of variables : 8 ( 1 sgn)
% SPC : CNF_SAT_RFO_EQU_NUE
% Comments : Infinox says this has no finite (counter-) models.
%--------------------------------------------------------------------------
cnf(zero_is_not_s,axiom,
n0 != s(X) ).
cnf(successor_is_injective,axiom,
( s(X) != s(Y)
| X = Y ) ).
cnf(definition_add_0,axiom,
add(n0,Y) = Y ).
cnf(definition_add_s,axiom,
add(s(X),Y) = s(add(X,Y)) ).
cnf(consistency_of_add_commutative,negated_conjecture,
add(X,Y) = add(Y,X) ).
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