## TPTP Axioms File: LCL006+4.ax

```%------------------------------------------------------------------------------
% File     : LCL006+4 : TPTP v7.5.0. Released v3.3.0.
% Domain   : Logic Calculi (Propositional)
% Axioms   : Principia's axiomatization of propositional logic
% Version  : [RW10] axioms.
% English  :

% Refs     : [RW10]  Russell & Whitehead (1910), Principia Mathmatica
%          : [Hal]   Halleck (URL), John Halleck's Logic Systems
%          : [She06] Shen (2006), Automated Proofs of Equivalence of Modal
% Source   : [Hal]
% Names    :

% Status   : Satisfiable
% Syntax   : Number of formulae    :   10 (  10 unit)
%            Number of atoms       :   10 (   0 equality)
%            Maximal formula depth :    1 (   1 average)
%            Number of connectives :    0 (   0 ~  ;   0  |;   0  &)
%                                         (   0 <=>;   0 =>;   0 <=)
%                                         (   0 <~>;   0 ~|;   0 ~&)
%            Number of predicates  :   10 (  10 propositional; 0-0 arity)
%            Number of functors    :    0 (   0 constant; --- arity)
%            Number of variables   :    0 (   0 singleton;   0 !;   0 ?)
%            Maximal term depth    :    0 (   0 average)
% SPC      :

% Comments : Requires LCL006+0, LCL006+1
%------------------------------------------------------------------------------
%----Operator definitions to reduce everything to and & not
fof(principia_op_implies_or,axiom,op_implies_or).

fof(principia_op_and,axiom,op_and).

fof(principia_op_equiv,axiom,op_equiv).

%----The one explicit rule
fof(principia_modus_ponens,axiom,modus_ponens).

%----The axioms
fof(principia_r1,axiom,r1).

fof(principia_r2,axiom,r2).

fof(principia_r3,axiom,r3).

%----This is the redundant axiom in Principia
fof(principia_r4,axiom,r4).

fof(principia_r5,axiom,r5).

%----Admissible but not required for completeness. With it much more can
%----be done.
fof(substitution_of_equivalents,axiom,substitution_of_equivalents).

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