Chris@0: /*  $Id$
Chris@0: 
Chris@0:     Part of SWI-Prolog
Chris@0: 
Chris@0:     Author:        Jan Wielemaker
Chris@0:     E-mail:        jan@swi.psy.uva.nl
Chris@0:     WWW:           http://www.swi-prolog.org
Chris@0:     Copyright (C): 1985-2004, University of Amsterdam
Chris@0: 
Chris@0:     This program is free software; you can redistribute it and/or
Chris@0:     modify it under the terms of the GNU General Public License
Chris@0:     as published by the Free Software Foundation; either version 2
Chris@0:     of the License, or (at your option) any later version.
Chris@0: 
Chris@0:     This program is distributed in the hope that it will be useful,
Chris@0:     but WITHOUT ANY WARRANTY; without even the implied warranty of
Chris@0:     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
Chris@0:     GNU General Public License for more details.
Chris@0: 
Chris@0:     You should have received a copy of the GNU Lesser General Public
Chris@0:     License along with this library; if not, write to the Free Software
Chris@0:     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
Chris@0: 
Chris@0:     As a special exception, if you link this library with other files,
Chris@0:     compiled with a Free Software compiler, to produce an executable, this
Chris@0:     library does not by itself cause the resulting executable to be covered
Chris@0:     by the GNU General Public License. This exception does not however
Chris@0:     invalidate any other reasons why the executable file might be covered by
Chris@0:     the GNU General Public License.
Chris@0: */
Chris@0: 
Chris@0: :- module(rdf_entailment,
Chris@0: 	  [ rdf/3
Chris@0: 	  ]).
Chris@0: :- use_module(rdfql_runtime).			% runtime tests
Chris@0: :- use_module(library('semweb/rdf_db'),
Chris@0: 	      [ rdf_global_id/2,
Chris@0: 		rdf_subject/1
Chris@0: 	      ]).
Chris@0: 
Chris@0: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Chris@0: The function of an entailment module is  to provide an implementation of
Chris@0: rdf/3 that extends basic triple-lookup using the entailment rules of the
Chris@0: semantic web sub language of RDF.  This   one  does  (still a lousy) job
Chris@0: realising RDFS entailment on top of rdf_db.pl.
Chris@0: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
Chris@0: 
Chris@0: term_expansion((rdf(S0, P0, O0) :- Body0),
Chris@0: 	       (rdf(S,  P,  O)  :- rdf_db:Body)) :-
Chris@0: 	rdf_global_id(S0, S),
Chris@0: 	rdf_global_id(P0, P),
Chris@0: 	rdf_global_id(O0, O),
Chris@0: 	expand_goal(Body0, Body).
Chris@0: 
Chris@0: rdf(S, P, O) :-
Chris@0: 	rdf(S, P, O).
Chris@0: rdf(S, rdf:type, rdf:'Property') :-
Chris@0: 	rdf(_, S, _),
Chris@0: 	\+ rdf(S, rdf:type, rdf:'Property').
Chris@0: rdf(S, rdf:type, rdfs:'Resource') :-
Chris@0: 	rdf_subject(S),
Chris@0: 	\+ rdf(S, rdf:type, rdfs:'Resource').
Chris@0: rdf(S, serql:directSubClassOf, O) :- !,
Chris@0: 	rdf(S, rdfs:subClassOf, O).
Chris@0: rdf(S, serql:directType, O) :- !,
Chris@0: 	rdf(S, rdf:type, O).
Chris@0: rdf(S, serql:directSubPropertyOf, O) :- !,
Chris@0: 	rdf(S, rdfs:subPropertyOf, O).
Chris@0: 
Chris@0: 
Chris@0: 		 /*******************************
Chris@0: 		 *	       REGISTER		*
Chris@0: 		 *******************************/
Chris@0: 
Chris@0: :- multifile
Chris@0: 	serql:entailment/2.
Chris@0: 
Chris@0: serql:entailment(rdf, rdf_entailment).