% % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % %
%                                                                           %
% File:            logics.dtr                                               %
% Purpose:         define a variety of propositional logics                 %
% Author:          Gerald Gazdar, 24 March 1989                             %
% Email:           geraldg@cogs.sussex.ac.uk                                %
% Address:         COGS, Sussex University, Brighton BN1 9QH, UK            %
% Documentation:   S. Haack (1974) Deviant Logic, Cambridge: CUP, Appendix. %
% Related files:   boolean1.dtr, boolean2.dtr, quantifi.dtr                 %
% Version:         1.01                                                     %
%      Copyright (c) University of Sussex 1989.  All rights reserved.       %
%                                                                           %
% % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % %

Logic:
        <> == "<default>"
        <default> == third
        <not true> == false
        <not false> == true
        <or true true> == true
        <or true false> == true
        <or true third> == "<or third true>"
        <or false true> == true
        <or false false> == false
        <or false third> == "<or third false>"
        <and true true> == true
        <and true false> == false
        <and true third> == "<and third true>"
        <and false true> == false
        <and false false> == false
        <and false third> == "<and third false>".

Classical:
        <> == Logic
        <default> == '** UNDEFINED **'.

Bochvar_internal:
        <> == Logic
        <third> == 'paradoxical/meaningless'.

Bochvar_external:
        <> == Bochvar_internal
        <default> == false
        <not third> == true
        <or third true> == true.

Destouches_Fevrier_1:
        <> == Bochvar_internal
        <or third false> == false
        <third> == 'absolutely false'.

Destouches_Fevrier_2:
        <> == Destouches_Fevrier_1
        <and> == third
        <not> == Bochvar_external
        <or true true> == third
        <or false false> == third.

Kleene_weak:
        <> == Bochvar_internal
        <third> == 'indeterminable'.

Kleene_strong:
        <third> == 'indeterminable'
        <> == Lukasiewicz.                 % true for 'not', 'or', and 'and'
                                           % (but not for 'if' or 'iff')

Lukasiewicz:
        <> == Logic
        <or third true> == true
        <and third false> == false
        <third> == 'indeterminate/possible'.

Smiley_primary:
        <> == Bochvar_internal
        <third> == 'truth-valueless'.

Smiley_secondary:
        <> == Bochvar_external
        <third> == 'truth-valueless'.

Woodruff:
        <> == Kleene_strong
        <third> == 'truth-valueless'.

% % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % %

# hide Logic.

# show  <third>
        <not true>
        <not third>
        <not false>
        <or true true>
        <or true third>
        <or true false>
        <or third true>
        <or third third>
        <or third false>
        <or false true>
        <or false third>
        <or false false>
        <and true true>
        <and true third>
        <and true false>
        <and third true>
        <and third third>
        <and third false>
        <and false true>
        <and false third>
        <and false false>.

% % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % %

% The next line is the Revision Control System Id: do not delete it.
% $Id: archive.dtr,v 1.1 1997/04/09 20:40:33 root Exp $