- From: Michael Kifer <kifer@cs.sunysb.edu>
- Date: Sat, 27 May 2006 19:34:17 -0400
- To: "Peter F. Patel-Schneider" <pfps@inf.unibz.it>
- Cc: public-rif-wg@w3.org
Peter, It is no big deal to be unitary by restricting the language to Datalog. You don't even need to limit it to a function-free sublanguage. In our roadmap the language was unitary also up to this point. The issue is how to build such a system in an extensible way so that it could be extended to satisfy most of the RIF requirements. --michael > A Proposal for a Unitary Language for RIF Phase 1 > > Peter F. Patel-Schneider > > Overview: > > 1/ The language of RIF Phase 1 is function-free Horn clauses. There > is a human-readable, functional-style syntax, plus an XML > interchange syntax. > > 2/ RIF Phase 1 includes predicates for the reasonable XML Schema > datatypes, plus various built-in predicates over these datatypes. > > 3/ A RIF Phase 1 knowledge base is a set of RIF Phase 1 documents plus > an optional set of OWL DL documents closed under OWL imports. > > 4/ The meaning of a RIF Phase 1 knowledge base is given by a standard model-theoretical semantics. > > 5/ Compliance for formalism X will be determined by the presence of a > non-trivial subset of X that can be mapped into RIF Phase 1 > knowledge bases in a deduction-preserving mapping. > > > Functional-style Syntax for RIF Phase 1: > > This syntax is a modification of the previous proposed syntax > from http://lists.w3.org/Archives/Public/public-rif-wg/2006Apr/0068.html > > Data ::= RDF typed or untyped data value > Ind ::= URI > Var ::= '?' name > Rel ::= URI > Term ::= Data | Ind | Var > Atom ::= Rel '(' Term* ')' | Term '=' Term > Rule ::= Atom <- Atom* > > Each variable in the consequent of a rule must also be present in the > antecedent. > > > XML INTERCHANGE SYNTAX > > TBD > > > SEMANTICS > > An interpretation is an extension of an OWL DL interpretation > (http://www.w3.org/TR/owl-semantics/direct.html), extending the > vocabulary to include RIF relation names and mapping them to tuples > over R union LV. RIF relation names that are OWL DL class names, > datatype names, individual-valued property names, data-valued property > names, or annotation property names have the same extension as given > by the appropriate part of the OWL semantics. > > A RIF rule is true in a RIF interpretation precisely when every > mapping from variables in the rule into R union LV that makes each > atom in the antecedent of the rule true in the obvious extension of > the OWL DL semantics also makes the consequent in the rule true in the > same way. > > > COMPLIANCE > > Compliance for formalism X will be measured as follows. > a/ Partial mappings will be provided between the syntaxes of X and RIF > Phase 1, including mappings between X's data language and OWL DL. > b/ A subset of RIF Phase 1 will be identified as being X-compliant. > c/ For that subset the deductive behaviour of X must mirror reasoning > in the RIF Phase 1 in the sense that ground consequences for > knowledge bases in this subset are the same for RIF Phase 1 and its > mapping into the syntax of X. > > Compliance of a rule system with RIF Phase 1 will be defined as follows. > 1/ The formalism underlying the rule system must be RIF Phase 1 > compliant as defined above. > 2/ There must be a tool that implements the syntax mapping. > 3/ There must be a comprehensive set of RIF knowledge bases for which > the equivalence of deductive behaviour has been reasonably demonstrated.
Received on Saturday, 27 May 2006 23:34:33 UTC