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Re: A proposal for a unitary RIF phase 1

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
Message-ID: <27663.1148772857@kiferserv.kiferhome.com>


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.


> 	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.
> 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 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

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