## TPTP Problem File: SEV234^5.p

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```%------------------------------------------------------------------------------
% File     : SEV234^5 : TPTP v7.5.0. Released v4.0.0.
% Domain   : Set Theory (Sets of sets)
% Problem  : TPS problem BLEDSOE-FENG-SV-10
% Version  : Especial.
% English  : If a set B has the property that every x in B has a nbhd D
%            subset B, then B is open.

% Refs     : [BF93]  Bledsoe & Feng (1993), SET-VAR
%          : [Bro09] Brown (2009), Email to Geoff Sutcliffe
% Source   : [Bro09]
% Names    : tps_0452 [Bro09]
%          : BLEDSOE-FENG-SV-10 [TPS]
%          : Example 10 [BF93]

% Status   : Theorem
% Rating   : 1.00 v4.0.0
% Syntax   : Number of formulae    :    2 (   0 unit;   1 type;   0 defn)
%            Number of atoms       :   24 (   1 equality;  19 variable)
%            Maximal formula depth :   12 (   8 average)
%            Number of connectives :   21 (   0   ~;   0   |;   4   &;  11   @)
%                                         (   0 <=>;   6  =>;   0  <=;   0 <~>)
%                                         (   0  ~|;   0  ~&)
%            Number of type conns  :    9 (   9   >;   0   *;   0   +;   0  <<)
%            Number of symbols     :    3 (   1   :;   0   =)
%            Number of variables   :    9 (   0 sgn;   6   !;   2   ?;   1   ^)
%                                         (   9   :;   0  !>;   0  ?*)
%                                         (   0  @-;   0  @+)
% SPC      : TH0_THM_EQU_NAR

% Comments : This problem is from the TPS library. Copyright (c) 2009 The TPS
%            project in the Department of Mathematical Sciences at Carnegie
%          : Polymorphic definitions expanded.
%------------------------------------------------------------------------------
thf(cOPEN,type,(
cOPEN: ( \$i > \$o ) > \$o )).

thf(cBLEDSOE_FENG_SV_10_pme,conjecture,
( ! [D: \$i > \$o,G: ( \$i > \$o ) > \$o] :
( ( ! [Xx: \$i > \$o] :
( ( G @ Xx )
=> ( cOPEN @ Xx ) )
& ( D
= ( ^ [Xx: \$i] :
? [S: \$i > \$o] :
( ( G @ S )
& ( S @ Xx ) ) ) ) )
=> ( cOPEN @ D ) )
=> ! [B: \$i > \$o] :
( ! [Xx: \$i] :
( ( B @ Xx )
=> ? [D: \$i > \$o] :
( ( cOPEN @ D )
& ( D @ Xx )
& ! [Xx0: \$i] :
( ( D @ Xx0 )
=> ( B @ Xx0 ) ) ) )
=> ( cOPEN @ B ) ) )).

%------------------------------------------------------------------------------
```