DAML Language Breakout Deborah L. McGuinness Knowledge Systems Laboratory Stanford University www.ksl.stanford.edu 2/15/01 Topics Reification Defaults/Non-Monotonicity Proof Checking Concrete vs. abstract domains (pre-defined types vs. user-defined types) (datatypes vs. classes) 2 Knowledge Systems Laboratory, Stanford University Reification (from dictionary: To regard or treat (an abstraction) as if it had concrete or material existence.) Requirement: Need to make statements about statements. Extensive discussion concerning potential pitfalls, usage in rdf, relationship to RDF, requirements Conclusion – if we include reification, we will expect problems Speculation – we may not be able to avoid modalities as long as we might have thought. 3 Knowledge Systems Laboratory, Stanford University Defaults/Rules Currently no default/rule/negation as failure capability in DAML+OIL Agreement that some solution is needed Consider some mechanism on top of the core language Observation that negation as failure in rule systems has long history of usage, tractability, etc. Action Items – form rule mailing list (Ben Grosof will seed the list) Small group followup meeting on topic 4 Knowledge Systems Laboratory, Stanford University Proof Checks Discussion on non-monotonicity led to a discussion of possibly checking non-monotonic proofs Discussion followed on proof checks of (possibly partial) deductions Can either trust reasoners or just check their proofs Proof checking requires tractable proof checking systems Followup among interested parties 5 Knowledge Systems Laboratory, Stanford University Concrete Data Types Consensus that concrete data type (numbers, strings, etc) are necessary Consensus around basic proposal initiated by Horrocks and Patel-Schneider Technical discussion about rdf syntax. Peter (and Ian and Frank) will provide a modified proposal taking into account Connolly’s document http://www.w3.org/2001/01/ct24 Expectation is that this will be included in the language prior to semantic web activity 6 Knowledge Systems Laboratory, Stanford University Other issues? Send email to rdf-logic mailing list (or [email protected]) 7 Knowledge Systems Laboratory, Stanford University Background Attended by most of ad-hoc committee (physically or virtually) Solicited feedback on current language and wishes for modifications/extensions No feedback on current language other than extensions 8 Knowledge Systems Laboratory, Stanford University
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