## TPTP Problem File: SEU585^2.p

View Solutions - Solve Problem

```%------------------------------------------------------------------------------
% File     : SEU585^2 : TPTP v7.1.0. Released v3.7.0.
% Domain   : Set Theory
% Problem  : Preliminary Notions - Ops on Sets - Unions and Intersections
% Version  : Especial > Reduced > Especial.
% English  : (! A:i.! B:i.! x:i.! phi:o.in x (binunion A B) ->
%            (in x A -> phi) -> (in x B -> phi) -> phi)

% Refs     : [Bro08] Brown (2008), Email to G. Sutcliffe
% Source   : [Bro08]
% Names    : ZFC087l [Bro08]

% Status   : Theorem
% Rating   : 0.12 v7.1.0, 0.38 v7.0.0, 0.29 v6.4.0, 0.33 v6.3.0, 0.40 v6.2.0, 0.14 v6.0.0, 0.29 v5.5.0, 0.33 v5.4.0, 0.40 v5.3.0, 0.20 v5.1.0, 0.40 v5.0.0, 0.20 v4.1.0, 0.00 v4.0.1, 0.67 v3.7.0
% Syntax   : Number of formulae    :   13 (   0 unit;   8 type;   4 defn)
%            Number of atoms       :   65 (   6 equality;  34 variable)
%            Maximal formula depth :   14 (   6 average)
%            Number of connectives :   48 (   0   ~;   0   |;   0   &;  30   @)
%                                         (   0 <=>;  18  =>;   0  <=;   0 <~>)
%                                         (   0  ~|;   0  ~&)
%            Number of type conns  :    7 (   7   >;   0   *;   0   +;   0  <<)
%            Number of symbols     :   10 (   8   :;   0   =)
%            Number of variables   :   16 (   0 sgn;  14   !;   0   ?;   2   ^)
%                                         (  16   :;   0  !>;   0  ?*)
%                                         (   0  @-;   0  @+)
% SPC      : TH0_THM_EQU_NAR

%          :
%------------------------------------------------------------------------------
thf(in_type,type,(
in: \$i > \$i > \$o )).

thf(emptyset_type,type,(
emptyset: \$i )).

setadjoin: \$i > \$i > \$i )).

thf(setunion_type,type,(
setunion: \$i > \$i )).

= ( ! [Xx: \$i,A: \$i,Xy: \$i] :
( ( in @ Xy @ ( setadjoin @ Xx @ A ) )
=> ! [Xphi: \$o] :
( ( ( Xy = Xx )
=> Xphi )
=> ( ( ( in @ Xy @ A )
=> Xphi )
=> Xphi ) ) ) ) )).

thf(setunionE_type,type,(
setunionE: \$o )).

thf(setunionE,definition,
( setunionE
= ( ! [A: \$i,Xx: \$i] :
( ( in @ Xx @ ( setunion @ A ) )
=> ! [Xphi: \$o] :
( ! [B: \$i] :
( ( in @ Xx @ B )
=> ( ( in @ B @ A )
=> Xphi ) )
=> Xphi ) ) ) )).

thf(uniqinunit_type,type,(
uniqinunit: \$o )).

thf(uniqinunit,definition,
( uniqinunit
= ( ! [Xx: \$i,Xy: \$i] :
( ( in @ Xx @ ( setadjoin @ Xy @ emptyset ) )
=> ( Xx = Xy ) ) ) )).

thf(binunion_type,type,(
binunion: \$i > \$i > \$i )).

thf(binunion,definition,
( binunion
= ( ^ [Xx: \$i,Xy: \$i] :
( setunion @ ( setadjoin @ Xx @ ( setadjoin @ Xy @ emptyset ) ) ) ) )).

thf(binunionEcases,conjecture,