%--------------------------------------------------------------------------
% File     : SET164-6 : TPTP v8.2.0. Bugfixed v2.2.0.
% Domain   : Set Theory
% Problem  : Idempotency of union
% Version  : [Qua92] axioms.
% English  :

% Refs     : [BL+86] Boyer et al. (1986), Set Theory in First-Order Logic:
%          : [Qua92] Quaife (1992), Automated Deduction in von Neumann-Bern
% Source   : [Quaife]
% Names    : U6 [Qua92]

% Status   : Unknown
% Rating   : 1.00 v2.1.0
% Syntax   :

% Comments : Quaife proves all these problems by augmenting the axioms with
%            all previously proved theorems. With a few exceptions (the
%            problems that correspond to [BL+86] problems), the TPTP has
%            retained the order in which Quaife presents the problems. The
%            user may create an augmented version of this problem by adding
%            all previously proved theorems (the ones that correspond to
%            [BL+86] are easily identified and positioned using Quaife's
%            naming scheme).
%          : Used as a demodulator by Quaife.
% Bugfixes : v1.0.1 - Bugfix in SET004-1.ax.
%          : v2.1.0 - Bugfix in SET004-0.ax.
%          : v2.2.0 - Renamed to SET002-6.p.
%--------------------------------------------------------------------------