Re: Action Items

From: Harold Boley (boley@informatik.uni-kl.de)
Date: 02/15/03

  • Next message: Mike Dean: "Joint Committee telecon today 18 February"
    Hi Stefan,
    
    > Harold: Pointing to rule classification in RuleML
    
    http://www.ruleml.org/indesign.html#RuleML-hierarchy
    
    >              Sending example how rules could interact with XML
    
    1) RuleML is based on a Web Data Model Unifying XML and RDF:
    http://www.dfki.uni-kl.de/~boley/xmlrdf.html
    http://www.ruleml.org/indtd0.8.html#Context
    
    2) RuleML will use XML Schema, Part 2, Datatypes, as a basis
    for its built-ins. This will provide a RuleML-OWL bridge
    right at the foundational data level.
    
    3) RuleML rules can process XML elements encoded as cterms.
    
    The direct use of XML elements as terms would be possible via
    a kind of (Lisp-inspired) XML-quoting mechanism:
    
    <quote>
      <your-well-formed-xml-element>
      . . .
      </your-well-formed-xml-element>
    </quote>
    
    For allowing such terms in, say, the atomic formulas of the Horn-Logic
    RuleML Sublanguage (http://www.ruleml.org/dtd/0.8/ruleml-hornlog.dtd),
    the definition of atoms could be extended via "| quote", e.g. thus:
    
    <!ELEMENT atom ((_opr, (ind | var | cterm | quote)*) |
                          ((ind | var | cterm | quote)+, _opr))>
    
    However, for the quote child element we would need an extended DTD meta-
    syntax, e.g. of the form
    
    <!ELEMENT quote (#WFDATA)>
    
    expressing that quote contains Well-Formed DATA, which looks similar to
    
    <!ELEMENT quote (#PCDATA)>
    
    but specifies an arbitrary well-formed XML element that doesn't need
    to be valid w.r.t. any - more specific - DTD. (Instead of just a single
    wf XML element, we could also allow an entire forest of wf XML elements
    within such a quote element.)
    
    For example, a binary mirror fact over wf XML elements could be written
    in such a 'quoting' RuleML as follows:
    
    <fact>
      <_head>
        <atom>
          <_opr><rel>mirror</rel></_opr>
          <quote>
            <a>
              <b/>
              <c/>
            </a>
          </quote>
          <quote>
            <a>
              <c/>
              <b/>
            </a>
          </quote>
        </atom>
      </_head>
    </fact>
    
    Best,
    Harold
    


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