TPTP Problem File: RAL036^1.p

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%------------------------------------------------------------------------------
% File     : RAL036^1 : TPTP v7.5.0. Released v7.0.0.
% Domain   : Real Algebra (Functions)
% Problem  : International Mathematical Olympiad, 1993, Problem 5
% Version  : [Mat16] axioms : Especial.
% English  : Does there exist a function f : N -> N such that f(1) = 2, 
%            f(f(n)) = f(n) + n for all n in N, and f(n) < f(n + 1) for all 
%            n in N?

% Refs     : [Mat16] Matsuzaki (2016), Email to Geoff Sutcliffe
%          : [MI+16] Matsuzaki et al. (2016), Race against the Teens - Benc
% Source   : [Mat16]
% Names    : IMO-1993-5.p [Mat16]

% Status   : Theorem
% Rating   : ? v7.0.0
% Syntax   : Number of formulae    : 3485 (   0 unit;1199 type;   0 defn)
%            Number of atoms       : 45318 (2210 equality;22713 variable)
%            Maximal formula depth :   35 (   9 average)
%            Number of connectives : 39611 ( 104   ~; 233   |;1175   &;35972   @)
%                                         (1095 <=>;1032  =>;   0  <=;   0 <~>)
%                                         (   0  ~|;   0  ~&)
%            Number of type conns  : 2409 (2409   >;   0   *;   0   +;   0  <<)
%            Number of symbols     : 1246 (1199   :;   0   =;   0  @=)
%                                         (   0  !!;   0  ??;   0 @@+;   0 @@-)
%            Number of variables   : 8057 (  66 sgn;7086   !; 430   ?; 405   ^)
%                                         (8057   :; 136  !>;   0  ?*)
%                                         (   0  @-;   0  @+)
%            Arithmetic symbols    : 1975 (   6 prd;   9 fun;  23 num;1937 var)
% SPC      : TH1_THM_EQU_ARI

% Comments : Theory: ZF; Score: 7; Author: Yiyang Zhan;
%            Generated: 2014-12-10
%------------------------------------------------------------------------------
include('Axioms/MAT001^0.ax').
%------------------------------------------------------------------------------
thf(p,conjecture,(
    ? [V_f: ( $int > $int )] :
      ( ( ( V_f @ 1 )
        = 2 )
      & ! [V_n: $int] :
          ( ( 'int.is-natural-number/1' @ V_n )
         => ( ( 'int.is-natural-number/1' @ ( V_f @ V_n ) )
            & ( ( V_f @ ( V_f @ V_n ) )
              = ( $sum @ ( V_f @ V_n ) @ V_n ) )
            & ( $less @ ( V_f @ V_n ) @ ( V_f @ ( $sum @ V_n @ 1 ) ) ) ) ) ) )).

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