TSTP Solution File: LCL866^1 by Lash---1.13

View Problem - Process Solution

%------------------------------------------------------------------------------
% File     : Lash---1.13
% Problem  : LCL866^1 : TPTP v8.1.2. Bugfixed v5.0.0.
% Transfm  : none
% Format   : tptp:raw
% Command  : lash -P picomus -M modes -p tstp -t %d %s

% Computer : n026.cluster.edu
% Model    : x86_64 x86_64
% CPU      : Intel(R) Xeon(R) CPU E5-2620 v4 2.10GHz
% Memory   : 8042.1875MB
% OS       : Linux 3.10.0-693.el7.x86_64
% CPULimit : 300s
% WCLimit  : 300s
% DateTime : Thu Aug 31 08:05:22 EDT 2023

% Result   : Theorem 0.21s 0.50s
% Output   : Proof 0.21s
% Verified : 
% SZS Type : Refutation
%            Derivation depth      :    6
%            Number of leaves      :   84
% Syntax   : Number of formulae    :   97 (  55 unt;   4 typ;  34 def)
%            Number of atoms       :  241 (  43 equ;   4 cnn)
%            Maximal formula atoms :    4 (   2 avg)
%            Number of connectives :  510 ( 102   ~;  28   |;   8   &; 279   @)
%                                         (  20 <=>;  73  =>;   0  <=;   0 <~>)
%            Maximal formula depth :   11 (   3 avg)
%            Number of types       :    2 (   0 usr)
%            Number of type conns  :   66 (  66   >;   0   *;   0   +;   0  <<)
%            Number of symbols     :   61 (  57 usr;  59 con; 0-2 aty)
%            Number of variables   :  167 (  68   ^;  93   !;   6   ?; 167   :)

% Comments : 
%------------------------------------------------------------------------------
thf(ty_eigen__6,type,
    eigen__6: $i ).

thf(ty_eigen__8,type,
    eigen__8: $i ).

thf(ty_eigen__4,type,
    eigen__4: $i ).

thf(ty_eigen__0,type,
    eigen__0: $i > $i > $o ).

thf(h0,assumption,
    ! [X1: $i > $o,X2: $i] :
      ( ( X1 @ X2 )
     => ( X1 @ ( eps__0 @ X1 ) ) ),
    introduced(assumption,[]) ).

thf(eigendef_eigen__6,definition,
    ( eigen__6
    = ( eps__0
      @ ^ [X1: $i] :
          ~ ! [X2: $i] :
              ( ~ ( ( eigen__0 @ eigen__4 @ X1 )
                 => ~ ( eigen__0 @ X1 @ X2 ) )
             => ( eigen__0 @ eigen__4 @ X2 ) ) ) ),
    introduced(definition,[new_symbols(definition,[eigen__6])]) ).

thf(eigendef_eigen__8,definition,
    ( eigen__8
    = ( eps__0
      @ ^ [X1: $i] :
          ~ ( ~ ( ( eigen__0 @ eigen__4 @ eigen__6 )
               => ~ ( eigen__0 @ eigen__6 @ X1 ) )
           => ( eigen__0 @ eigen__4 @ X1 ) ) ) ),
    introduced(definition,[new_symbols(definition,[eigen__8])]) ).

thf(eigendef_eigen__4,definition,
    ( eigen__4
    = ( eps__0
      @ ^ [X1: $i] :
          ~ ! [X2: $i,X3: $i] :
              ( ~ ( ( eigen__0 @ X1 @ X2 )
                 => ~ ( eigen__0 @ X2 @ X3 ) )
             => ( eigen__0 @ X1 @ X3 ) ) ) ),
    introduced(definition,[new_symbols(definition,[eigen__4])]) ).

thf(sP1,plain,
    ( sP1
  <=> ( ( eigen__0 @ eigen__4 @ eigen__6 )
     => ~ ( eigen__0 @ eigen__6 @ eigen__8 ) ) ),
    introduced(definition,[new_symbols(definition,[sP1])]) ).

thf(sP2,plain,
    ( sP2
  <=> ! [X1: $i,X2: $i,X3: $i] :
        ( ~ ( ( eigen__0 @ X1 @ X2 )
           => ~ ( eigen__0 @ X1 @ X3 ) )
       => ( eigen__0 @ X2 @ X3 ) ) ),
    introduced(definition,[new_symbols(definition,[sP2])]) ).

thf(sP3,plain,
    ( sP3
  <=> ! [X1: $i,X2: $i,X3: $i] :
        ( ~ ( ( eigen__0 @ X1 @ X2 )
           => ~ ( eigen__0 @ X2 @ X3 ) )
       => ( eigen__0 @ X1 @ X3 ) ) ),
    introduced(definition,[new_symbols(definition,[sP3])]) ).

thf(sP4,plain,
    ( sP4
  <=> ( eigen__0 @ eigen__4 @ eigen__6 ) ),
    introduced(definition,[new_symbols(definition,[sP4])]) ).

thf(sP5,plain,
    ( sP5
  <=> ( sP4
     => ( eigen__0 @ eigen__6 @ eigen__4 ) ) ),
    introduced(definition,[new_symbols(definition,[sP5])]) ).

thf(sP6,plain,
    ( sP6
  <=> ( eigen__0 @ eigen__6 @ eigen__4 ) ),
    introduced(definition,[new_symbols(definition,[sP6])]) ).

thf(sP7,plain,
    ( sP7
  <=> ! [X1: $i] :
        ( ~ ( sP6
           => ~ ( eigen__0 @ eigen__6 @ X1 ) )
       => ( eigen__0 @ eigen__4 @ X1 ) ) ),
    introduced(definition,[new_symbols(definition,[sP7])]) ).

thf(sP8,plain,
    ( sP8
  <=> ! [X1: $i] :
        ( ~ ( sP4
           => ~ ( eigen__0 @ eigen__6 @ X1 ) )
       => ( eigen__0 @ eigen__4 @ X1 ) ) ),
    introduced(definition,[new_symbols(definition,[sP8])]) ).

thf(sP9,plain,
    ( sP9
  <=> ! [X1: $i] :
        ( ( eigen__0 @ eigen__4 @ X1 )
       => ( eigen__0 @ X1 @ eigen__4 ) ) ),
    introduced(definition,[new_symbols(definition,[sP9])]) ).

thf(sP10,plain,
    ( sP10
  <=> ( ! [X1: $i,X2: $i] :
          ( ( eigen__0 @ X1 @ X2 )
         => ( eigen__0 @ X2 @ X1 ) )
     => ~ sP2 ) ),
    introduced(definition,[new_symbols(definition,[sP10])]) ).

thf(sP11,plain,
    ( sP11
  <=> ! [X1: $i,X2: $i] :
        ( ~ ( ( eigen__0 @ eigen__4 @ X1 )
           => ~ ( eigen__0 @ X1 @ X2 ) )
       => ( eigen__0 @ eigen__4 @ X2 ) ) ),
    introduced(definition,[new_symbols(definition,[sP11])]) ).

thf(sP12,plain,
    ( sP12
  <=> ! [X1: $i,X2: $i] :
        ( ~ ( ( eigen__0 @ eigen__6 @ X1 )
           => ~ ( eigen__0 @ eigen__6 @ X2 ) )
       => ( eigen__0 @ X1 @ X2 ) ) ),
    introduced(definition,[new_symbols(definition,[sP12])]) ).

thf(sP13,plain,
    ( sP13
  <=> ( eigen__0 @ eigen__4 @ eigen__8 ) ),
    introduced(definition,[new_symbols(definition,[sP13])]) ).

thf(sP14,plain,
    ( sP14
  <=> ! [X1: $i,X2: $i] :
        ( ( eigen__0 @ X1 @ X2 )
       => ( eigen__0 @ X2 @ X1 ) ) ),
    introduced(definition,[new_symbols(definition,[sP14])]) ).

thf(sP15,plain,
    ( sP15
  <=> ( eigen__0 @ eigen__6 @ eigen__8 ) ),
    introduced(definition,[new_symbols(definition,[sP15])]) ).

thf(sP16,plain,
    ( sP16
  <=> ( ~ ( sP3
         => ~ sP14 )
     => ~ sP2 ) ),
    introduced(definition,[new_symbols(definition,[sP16])]) ).

thf(sP17,plain,
    ( sP17
  <=> ( ~ ( sP6
         => ~ sP15 )
     => sP13 ) ),
    introduced(definition,[new_symbols(definition,[sP17])]) ).

thf(sP18,plain,
    ( sP18
  <=> ( sP6
     => ~ sP15 ) ),
    introduced(definition,[new_symbols(definition,[sP18])]) ).

thf(sP19,plain,
    ( sP19
  <=> ( ~ sP1
     => sP13 ) ),
    introduced(definition,[new_symbols(definition,[sP19])]) ).

thf(sP20,plain,
    ( sP20
  <=> ( sP3
     => ~ sP14 ) ),
    introduced(definition,[new_symbols(definition,[sP20])]) ).

thf(def_meq_ind,definition,
    ( meq_ind
    = ( ^ [X1: mu,X2: mu,X3: $i] : ( X1 = X2 ) ) ) ).

thf(def_meq_prop,definition,
    ( meq_prop
    = ( ^ [X1: $i > $o,X2: $i > $o,X3: $i] :
          ( ( X1 @ X3 )
          = ( X2 @ X3 ) ) ) ) ).

thf(def_mnot,definition,
    ( mnot
    = ( ^ [X1: $i > $o,X2: $i] : ( (~) @ ( X1 @ X2 ) ) ) ) ).

thf(def_mor,definition,
    ( mor
    = ( ^ [X1: $i > $o,X2: $i > $o,X3: $i] :
          ( ( X1 @ X3 )
          | ( X2 @ X3 ) ) ) ) ).

thf(def_mand,definition,
    ( mand
    = ( ^ [X1: $i > $o,X2: $i > $o] : ( mnot @ ( mor @ ( mnot @ X1 ) @ ( mnot @ X2 ) ) ) ) ) ).

thf(def_mimplies,definition,
    ( mimplies
    = ( ^ [X1: $i > $o,X2: $i > $o] : ( mor @ ( mnot @ X1 ) @ X2 ) ) ) ).

thf(def_mimplied,definition,
    ( mimplied
    = ( ^ [X1: $i > $o,X2: $i > $o] : ( mor @ ( mnot @ X2 ) @ X1 ) ) ) ).

thf(def_mequiv,definition,
    ( mequiv
    = ( ^ [X1: $i > $o,X2: $i > $o] : ( mand @ ( mimplies @ X1 @ X2 ) @ ( mimplies @ X2 @ X1 ) ) ) ) ).

thf(def_mxor,definition,
    ( mxor
    = ( ^ [X1: $i > $o,X2: $i > $o] : ( mnot @ ( mequiv @ X1 @ X2 ) ) ) ) ).

thf(def_mforall_ind,definition,
    ( mforall_ind
    = ( ^ [X1: mu > $i > $o,X2: $i] :
        ! [X3: mu] : ( X1 @ X3 @ X2 ) ) ) ).

thf(def_mforall_prop,definition,
    ( mforall_prop
    = ( ^ [X1: ( $i > $o ) > $i > $o,X2: $i] :
        ! [X3: $i > $o] : ( X1 @ X3 @ X2 ) ) ) ).

thf(def_mexists_ind,definition,
    ( mexists_ind
    = ( ^ [X1: mu > $i > $o] :
          ( mnot
          @ ( mforall_ind
            @ ^ [X2: mu] : ( mnot @ ( X1 @ X2 ) ) ) ) ) ) ).

thf(def_mexists_prop,definition,
    ( mexists_prop
    = ( ^ [X1: ( $i > $o ) > $i > $o] :
          ( mnot
          @ ( mforall_prop
            @ ^ [X2: $i > $o] : ( mnot @ ( X1 @ X2 ) ) ) ) ) ) ).

thf(def_mtrue,definition,
    ( mtrue
    = ( ^ [X1: $i] : $true ) ) ).

thf(def_mfalse,definition,
    ( mfalse
    = ( mnot @ mtrue ) ) ).

thf(def_mbox,definition,
    ( mbox
    = ( ^ [X1: $i > $i > $o,X2: $i > $o,X3: $i] :
        ! [X4: $i] :
          ( ( (~) @ ( X1 @ X3 @ X4 ) )
          | ( X2 @ X4 ) ) ) ) ).

thf(def_mdia,definition,
    ( mdia
    = ( ^ [X1: $i > $i > $o,X2: $i > $o] : ( mnot @ ( mbox @ X1 @ ( mnot @ X2 ) ) ) ) ) ).

thf(def_mreflexive,definition,
    ( mreflexive
    = ( ^ [X1: $i > $i > $o] :
        ! [X2: $i] : ( X1 @ X2 @ X2 ) ) ) ).

thf(def_msymmetric,definition,
    ( msymmetric
    = ( ^ [X1: $i > $i > $o] :
        ! [X2: $i,X3: $i] :
          ( ^ [X4: $o,X5: $o] :
              ( X4
             => X5 )
          @ ( X1 @ X2 @ X3 )
          @ ( X1 @ X3 @ X2 ) ) ) ) ).

thf(def_mserial,definition,
    ( mserial
    = ( ^ [X1: $i > $i > $o] :
        ! [X2: $i] :
        ? [X3: $i] : ( X1 @ X2 @ X3 ) ) ) ).

thf(def_mtransitive,definition,
    ( mtransitive
    = ( ^ [X1: $i > $i > $o] :
        ! [X2: $i,X3: $i,X4: $i] :
          ( ^ [X5: $o,X6: $o] :
              ( X5
             => X6 )
          @ ( ( X1 @ X2 @ X3 )
            & ( X1 @ X3 @ X4 ) )
          @ ( X1 @ X2 @ X4 ) ) ) ) ).

thf(def_meuclidean,definition,
    ( meuclidean
    = ( ^ [X1: $i > $i > $o] :
        ! [X2: $i,X3: $i,X4: $i] :
          ( ^ [X5: $o,X6: $o] :
              ( X5
             => X6 )
          @ ( ( X1 @ X2 @ X3 )
            & ( X1 @ X2 @ X4 ) )
          @ ( X1 @ X3 @ X4 ) ) ) ) ).

thf(def_mpartially_functional,definition,
    ( mpartially_functional
    = ( ^ [X1: $i > $i > $o] :
        ! [X2: $i,X3: $i,X4: $i] :
          ( ^ [X5: $o,X6: $o] :
              ( X5
             => X6 )
          @ ( ( X1 @ X2 @ X3 )
            & ( X1 @ X2 @ X4 ) )
          @ ( X3 = X4 ) ) ) ) ).

thf(def_mfunctional,definition,
    ( mfunctional
    = ( ^ [X1: $i > $i > $o] :
        ! [X2: $i] :
        ? [X3: $i] :
          ( ( X1 @ X2 @ X3 )
          & ! [X4: $i] :
              ( ^ [X5: $o,X6: $o] :
                  ( X5
                 => X6 )
              @ ( X1 @ X2 @ X4 )
              @ ( X3 = X4 ) ) ) ) ) ).

thf(def_mweakly_dense,definition,
    ( mweakly_dense
    = ( ^ [X1: $i > $i > $o] :
        ! [X2: $i,X3: $i,X4: $i] :
          ( ^ [X5: $o,X6: $o] :
              ( X5
             => X6 )
          @ ( X1 @ X2 @ X3 )
          @ ? [X5: $i] :
              ( ( X1 @ X2 @ X5 )
              & ( X1 @ X5 @ X3 ) ) ) ) ) ).

thf(def_mweakly_connected,definition,
    ( mweakly_connected
    = ( ^ [X1: $i > $i > $o] :
        ! [X2: $i,X3: $i,X4: $i] :
          ( ^ [X5: $o,X6: $o] :
              ( X5
             => X6 )
          @ ( ( X1 @ X2 @ X3 )
            & ( X1 @ X2 @ X4 ) )
          @ ( ( X1 @ X3 @ X4 )
            | ( X3 = X4 )
            | ( X1 @ X4 @ X3 ) ) ) ) ) ).

thf(def_mweakly_directed,definition,
    ( mweakly_directed
    = ( ^ [X1: $i > $i > $o] :
        ! [X2: $i,X3: $i,X4: $i] :
          ( ^ [X5: $o,X6: $o] :
              ( X5
             => X6 )
          @ ( ( X1 @ X2 @ X3 )
            & ( X1 @ X2 @ X4 ) )
          @ ? [X5: $i] :
              ( ( X1 @ X3 @ X5 )
              & ( X1 @ X4 @ X5 ) ) ) ) ) ).

thf(def_mvalid,definition,
    ( mvalid
    = ( ^ [X1: $i > $o] :
        ! [X2: $i] : ( X1 @ X2 ) ) ) ).

thf(def_minvalid,definition,
    ( minvalid
    = ( ^ [X1: $i > $o] :
        ! [X2: $i] : ( (~) @ ( X1 @ X2 ) ) ) ) ).

thf(def_msatisfiable,definition,
    ( msatisfiable
    = ( ^ [X1: $i > $o] :
        ? [X2: $i] : ( X1 @ X2 ) ) ) ).

thf(def_mcountersatisfiable,definition,
    ( mcountersatisfiable
    = ( ^ [X1: $i > $o] :
        ? [X2: $i] : ( (~) @ ( X1 @ X2 ) ) ) ) ).

thf(conj,conjecture,
    ! [X1: $i > $i > $o] :
      ( ( ~ ( ! [X2: $i,X3: $i] :
                ( ( X1 @ X2 @ X3 )
               => ( X1 @ X3 @ X2 ) )
           => ~ ! [X2: $i,X3: $i,X4: $i] :
                  ( ~ ( ( X1 @ X2 @ X3 )
                     => ~ ( X1 @ X2 @ X4 ) )
                 => ( X1 @ X3 @ X4 ) ) ) )
      = ( ~ ( ~ ( ! [X2: $i,X3: $i,X4: $i] :
                    ( ~ ( ( X1 @ X2 @ X3 )
                       => ~ ( X1 @ X3 @ X4 ) )
                   => ( X1 @ X2 @ X4 ) )
               => ~ ! [X2: $i,X3: $i] :
                      ( ( X1 @ X2 @ X3 )
                     => ( X1 @ X3 @ X2 ) ) )
           => ~ ! [X2: $i,X3: $i,X4: $i] :
                  ( ~ ( ( X1 @ X2 @ X3 )
                     => ~ ( X1 @ X2 @ X4 ) )
                 => ( X1 @ X3 @ X4 ) ) ) ) ) ).

thf(h1,negated_conjecture,
    ~ ! [X1: $i > $i > $o] :
        ( ( ~ ( ! [X2: $i,X3: $i] :
                  ( ( X1 @ X2 @ X3 )
                 => ( X1 @ X3 @ X2 ) )
             => ~ ! [X2: $i,X3: $i,X4: $i] :
                    ( ~ ( ( X1 @ X2 @ X3 )
                       => ~ ( X1 @ X2 @ X4 ) )
                   => ( X1 @ X3 @ X4 ) ) ) )
        = ( ~ ( ~ ( ! [X2: $i,X3: $i,X4: $i] :
                      ( ~ ( ( X1 @ X2 @ X3 )
                         => ~ ( X1 @ X3 @ X4 ) )
                     => ( X1 @ X2 @ X4 ) )
                 => ~ ! [X2: $i,X3: $i] :
                        ( ( X1 @ X2 @ X3 )
                       => ( X1 @ X3 @ X2 ) ) )
             => ~ ! [X2: $i,X3: $i,X4: $i] :
                    ( ~ ( ( X1 @ X2 @ X3 )
                       => ~ ( X1 @ X2 @ X4 ) )
                   => ( X1 @ X3 @ X4 ) ) ) ) ),
    inference(assume_negation,[status(cth)],[conj]) ).

thf(h2,assumption,
    ( ~ sP10 != ~ sP16 ),
    introduced(assumption,[]) ).

thf(h3,assumption,
    ~ sP10,
    introduced(assumption,[]) ).

thf(h4,assumption,
    ~ sP16,
    introduced(assumption,[]) ).

thf(h5,assumption,
    sP10,
    introduced(assumption,[]) ).

thf(h6,assumption,
    sP16,
    introduced(assumption,[]) ).

thf(h7,assumption,
    sP14,
    introduced(assumption,[]) ).

thf(h8,assumption,
    sP2,
    introduced(assumption,[]) ).

thf(1,plain,
    ( ~ sP18
    | ~ sP6
    | ~ sP15 ),
    inference(prop_rule,[status(thm)],]) ).

thf(2,plain,
    ( ~ sP17
    | sP18
    | sP13 ),
    inference(prop_rule,[status(thm)],]) ).

thf(3,plain,
    ( ~ sP7
    | sP17 ),
    inference(all_rule,[status(thm)],]) ).

thf(4,plain,
    ( ~ sP5
    | ~ sP4
    | sP6 ),
    inference(prop_rule,[status(thm)],]) ).

thf(5,plain,
    ( ~ sP9
    | sP5 ),
    inference(all_rule,[status(thm)],]) ).

thf(6,plain,
    ( ~ sP14
    | sP9 ),
    inference(all_rule,[status(thm)],]) ).

thf(7,plain,
    ( ~ sP12
    | sP7 ),
    inference(all_rule,[status(thm)],]) ).

thf(8,plain,
    ( ~ sP2
    | sP12 ),
    inference(all_rule,[status(thm)],]) ).

thf(9,plain,
    ( sP1
    | sP15 ),
    inference(prop_rule,[status(thm)],]) ).

thf(10,plain,
    ( sP1
    | sP4 ),
    inference(prop_rule,[status(thm)],]) ).

thf(11,plain,
    ( sP19
    | ~ sP13 ),
    inference(prop_rule,[status(thm)],]) ).

thf(12,plain,
    ( sP19
    | ~ sP1 ),
    inference(prop_rule,[status(thm)],]) ).

thf(13,plain,
    ( sP8
    | ~ sP19 ),
    inference(eigen_choice_rule,[status(thm),assumptions([h0])],[h0,eigendef_eigen__8]) ).

thf(14,plain,
    ( sP11
    | ~ sP8 ),
    inference(eigen_choice_rule,[status(thm),assumptions([h0])],[h0,eigendef_eigen__6]) ).

thf(15,plain,
    ( sP3
    | ~ sP11 ),
    inference(eigen_choice_rule,[status(thm),assumptions([h0])],[h0,eigendef_eigen__4]) ).

thf(16,plain,
    ( ~ sP20
    | ~ sP3
    | ~ sP14 ),
    inference(prop_rule,[status(thm)],]) ).

thf(17,plain,
    ( ~ sP16
    | sP20
    | ~ sP2 ),
    inference(prop_rule,[status(thm)],]) ).

thf(18,plain,
    $false,
    inference(prop_unsat,[status(thm),assumptions([h7,h8,h3,h4,h2,h1,h0])],[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,h7,h8,h4]) ).

thf(19,plain,
    $false,
    inference(tab_negimp,[status(thm),assumptions([h3,h4,h2,h1,h0]),tab_negimp(discharge,[h7,h8])],[h3,18,h7,h8]) ).

thf(h9,assumption,
    ~ sP20,
    introduced(assumption,[]) ).

thf(h10,assumption,
    sP3,
    introduced(assumption,[]) ).

thf(20,plain,
    ( ~ sP10
    | ~ sP14
    | ~ sP2 ),
    inference(prop_rule,[status(thm)],]) ).

thf(21,plain,
    $false,
    inference(prop_unsat,[status(thm),assumptions([h10,h7,h9,h8,h5,h6,h2,h1,h0])],[20,h5,h7,h8]) ).

thf(22,plain,
    $false,
    inference(tab_negimp,[status(thm),assumptions([h9,h8,h5,h6,h2,h1,h0]),tab_negimp(discharge,[h10,h7])],[h9,21,h10,h7]) ).

thf(23,plain,
    $false,
    inference(tab_negimp,[status(thm),assumptions([h5,h6,h2,h1,h0]),tab_negimp(discharge,[h9,h8])],[h6,22,h9,h8]) ).

thf(24,plain,
    $false,
    inference(tab_be,[status(thm),assumptions([h2,h1,h0]),tab_be(discharge,[h3,h4]),tab_be(discharge,[h5,h6])],[h2,19,23,h3,h4,h5,h6]) ).

thf(25,plain,
    $false,
    inference(tab_negall,[status(thm),assumptions([h1,h0]),tab_negall(discharge,[h2]),tab_negall(eigenvar,eigen__0)],[h1,24,h2]) ).

thf(26,plain,
    $false,
    inference(eigenvar_choice,[status(thm),assumptions([h1]),eigenvar_choice(discharge,[h0])],[25,h0]) ).

thf(0,theorem,
    ! [X1: $i > $i > $o] :
      ( ( ~ ( ! [X2: $i,X3: $i] :
                ( ( X1 @ X2 @ X3 )
               => ( X1 @ X3 @ X2 ) )
           => ~ ! [X2: $i,X3: $i,X4: $i] :
                  ( ~ ( ( X1 @ X2 @ X3 )
                     => ~ ( X1 @ X2 @ X4 ) )
                 => ( X1 @ X3 @ X4 ) ) ) )
      = ( ~ ( ~ ( ! [X2: $i,X3: $i,X4: $i] :
                    ( ~ ( ( X1 @ X2 @ X3 )
                       => ~ ( X1 @ X3 @ X4 ) )
                   => ( X1 @ X2 @ X4 ) )
               => ~ ! [X2: $i,X3: $i] :
                      ( ( X1 @ X2 @ X3 )
                     => ( X1 @ X3 @ X2 ) ) )
           => ~ ! [X2: $i,X3: $i,X4: $i] :
                  ( ~ ( ( X1 @ X2 @ X3 )
                     => ~ ( X1 @ X2 @ X4 ) )
                 => ( X1 @ X3 @ X4 ) ) ) ) ),
    inference(contra,[status(thm),contra(discharge,[h1])],[25,h1]) ).

%------------------------------------------------------------------------------
%----ORIGINAL SYSTEM OUTPUT
% 0.12/0.13  % Problem  : LCL866^1 : TPTP v8.1.2. Bugfixed v5.0.0.
% 0.12/0.14  % Command  : lash -P picomus -M modes -p tstp -t %d %s
% 0.14/0.35  % Computer : n026.cluster.edu
% 0.14/0.35  % Model    : x86_64 x86_64
% 0.14/0.35  % CPU      : Intel(R) Xeon(R) CPU E5-2620 v4 @ 2.10GHz
% 0.14/0.35  % Memory   : 8042.1875MB
% 0.14/0.35  % OS       : Linux 3.10.0-693.el7.x86_64
% 0.14/0.35  % CPULimit : 300
% 0.14/0.35  % WCLimit  : 300
% 0.14/0.35  % DateTime : Fri Aug 25 06:40:32 EDT 2023
% 0.14/0.35  % CPUTime  : 
% 0.21/0.50  % SZS status Theorem
% 0.21/0.50  % Mode: cade22grackle2xfee4
% 0.21/0.50  % Steps: 1343
% 0.21/0.50  % SZS output start Proof
% See solution above
%------------------------------------------------------------------------------