DAML Language Breakout

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• DAML Language Breakout
• Deborah L. McGuinness
• Knowledge Systems Laboratory
• Stanford University
• www.ksl.stanford.edu

2/15/01

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Topics

• Reification
• Defaults/Non-Monotonicity
• Proof Checking
• Concrete vs. abstract domains
• (pre-defined types vs. user-defined types)
• (datatypes vs. classes)

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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.

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Defaults/Rules

• Currently no default/rule/negation as failure
  capability in DAMLOIL
• 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

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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

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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 Connollys document
  http//www.w3.org/2001/01/ct24
• Expectation is that this will be included in the
  language prior to semantic web activity

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Other issues?

• Send email to rdf-logic mailing list
• (or dlm_at_ksl.stanford.edu)

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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