%==============================================================================
% Project:    SLP - An Interpreter for Super Logic Programs / Static Semantics
% Module:     test8.txt
% Purpose:    Distinction between conditional facts and rules
% Last Change:13.10.2001
% Language:   SLP
% Author:     Stefan Brass
% Email:      Stefan.Brass@informatik.uni-giessen.de, sbrass@sis.pitt.edu
% Address:    Universitaet Giessen, Arndtstr. 2, 35392 Giessen, Germany
% Copyright:  (c) 2001 by Stefan Brass
% Licence:    Distributed under the conditions of the GNU Public Licence.
%==============================================================================

% This simply tests the distinction between conditional facts and rules.
% It was the first test I used when I had implemented the rule data structures.
% By the way, it also does one hyperresolution step.

p :- q.
q :- r, not s.
p | q :- r, s, not u, not(w1 & w2).
p.
r | t :- not a, not (b & c), not d.
r :- not s.

% The following conditional facts should be listed:
%	p.
%	r | t :- not a, not (b & c), not d.
%	r :- not s.

% The following rules should be listed:
%	p :- q.
%	q :- r, not s.
%	p | q :- r, s, not u, not(w1 & w2).

% The following facts are derived (Hyperresolution Fixpoint):
%	p.
%	r | t :- not a, not (b & c), not d.
%	r :- not s.
%	q :- not s.

% The residual program is:
%	p.
%	q.
%	r.
% Occurrences of the negative literal not s are linked in the inverse order,
% therefore q is listed first.

$v.