%--------------------------------------------------------------------------
% File     : COL001-1 : TPTP v9.0.0. Released v1.0.0.
% Domain   : Combinatory Logic
% Problem  : Weak fixed point for S and K
% Version  : [WM88] (equality) axioms.
% English  : The weak fixed point property holds for the set P consisting
%            of the combinators S and K alone, where ((Sx)y)z = (xz)(yz)
%            and (Kx)y = x.

% Refs     : [Smu85] Smullyan (1978), To Mock a Mocking Bird and Other Logi
%          : [WM88]  Wos & McCune (1988), Challenge Problems Focusing on Eq
% Source   : [WM88]
% Names    : C1 [WM88]
%          : Problem 1 [WM88]

% Status   : Unsatisfiable
% Rating   : 0.18 v8.2.0, 0.29 v8.1.0, 0.30 v7.5.0, 0.29 v7.4.0, 0.35 v7.3.0, 0.32 v7.1.0, 0.22 v7.0.0, 0.21 v6.4.0, 0.26 v6.3.0, 0.24 v6.2.0, 0.21 v6.1.0, 0.12 v6.0.0, 0.29 v5.5.0, 0.21 v5.4.0, 0.13 v5.3.0, 0.17 v5.2.0, 0.14 v5.1.0, 0.20 v5.0.0, 0.21 v4.1.0, 0.18 v4.0.1, 0.21 v4.0.0, 0.23 v3.7.0, 0.11 v3.4.0, 0.12 v3.3.0, 0.07 v3.1.0, 0.11 v2.7.0, 0.00 v2.1.0, 0.13 v2.0.0
% Syntax   : Number of clauses     :    3 (   3 unt;   0 nHn;   1 RR)
%            Number of literals    :    3 (   3 equ;   1 neg)
%            Maximal clause size   :    1 (   1 avg)
%            Maximal term depth    :    4 (   2 avg)
%            Number of predicates  :    1 (   0 usr;   0 prp; 2-2 aty)
%            Number of functors    :    4 (   4 usr;   3 con; 0-2 aty)
%            Number of variables   :    6 (   1 sgn)
% SPC      : CNF_UNS_RFO_PEQ_UEQ

% Comments :
%--------------------------------------------------------------------------
cnf(s_definition,axiom,
    apply(apply(apply(s,X),Y),Z) = apply(apply(X,Z),apply(Y,Z)) ).

cnf(k_definition,axiom,
    apply(apply(k,X),Y) = X ).

cnf(prove_fixed_point,negated_conjecture,
    Y != apply(combinator,Y) ).

%--------------------------------------------------------------------------