Simple Common Logic SCL: A Constraint Language for the ODM

1
Simple Common Logic (SCL)A Constraint Language
for the ODM

• Elisa Kendall, Sandpiper Software, Inc.
• David Frankel, David Frankel Consulting
• Patrick Hayes, Institute for Human and Machine
  Cognition, University of West Florida
• Deborah McGuinness, Knowledge Systems Laboratory,
  Stanford University
• 21 September 2004

2
Motivation

• To ensure that the ODM meets Usage Scenarios and
  Goals requirements
• To provide a content language for agent
  communications that meets FIPA and the OMG Agents
  PSIG needs
• To support automatic selection, composition, and
  interoperation of Semantic Web Services where
  composition includes services that involve side
  effects, such as e-commerce services with credit
  card transactions
• To represent formulas, scientific theories, and
  technical knowledge
• For representation of pre- and post conditions,
  actions that change the state of the world,
  planning, complex constraints and preferences,
  etc.
• To support reasoning about action and change as
  well as understanding the consequences of some
  action within the context of a situation
• The declarative representation of such
  information requires first order logic

3
Why SCL?

• SCL FOL language for information exchange and
  transmission it allows for a variety of
  different syntactic forms, expressible within a
  common XML-based syntax, sharing a single
  semantics
• SCL is the foundation for the family of languages
  being standardized under the Common Logic charter
  by the ISO community (see http//cl.tamu.edu/ )
• Normative mappings from SCL to other commonly
  used KR languages, such as KIF and Conceptual
  Graphs, are defined in the ISO 24707
  specification
• Direct mappings from RDF Schema and OWL are in
  work, available at http//www.ihmc.us/users/phayes
  /SW2SCL.html, enabling SCL reasoners to leverage
  both ontologies expressed in OWL as well as SCL
  constraints developed in tools based on the ODM
• Other proposals currently in work by the W3C,
  such as RuleML, are not yet formal
  recommendations and are not supported by the ISO
  at this time

4
Evolution of KIF / CL / SCL

• The Knowledge Interchange Format (KIF)
  developed in the late 1980s
• KIF Reference Manual, Version 3.0
  http//ksl.stanford.edu/KSL_Abstracts/KSL-92-86.ht
  ml
• Several flavors of KIF have emerged since
• IDEF5 (1994) http//www.kbsi.com/technology/meth
  ods/sbont.htm
• Draft ANSI KIF (1998) http//logic.stanford.edu/
  kif/dpans.html
• FIPA KIF Content Specification Language (2000 /
  2001) http//www.fipa.org/specs/fipa00010/XC0001
  0C.html
• Draft ISO KIF Part 1 First Order KIF (2001)
  http//cl.tamu.edu/discuss/prop.html
• Draft IEEE SUO KIF (2002) http//suo.ieee.org/KI
  F/
• Common Logic (CL) initiative brought to ISO JTF 1
  / SC 32 / WG 2 on metadata standards by John Sowa
  (ANSI NCITS L8 March 2002) http//cl.tamu.edu/
  
• Languages initially proposed under the CL
  umbrella included KIF, Prolog, Conceptual Graphs,
  OCL, Z
• Intent was to be able to support vendor
  representations Cyc-L, Ontos, XSB, Haley
  Eclipse, NASA CLIPS

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SCL Metamodel Development Process

• Initiated development on a metamodel of ISO KIF,
  with intent to complete metamodels of both ISO
  KIF and draft ANSI KIF 9/2003
• Solicited help from Dave Frankel and Deb
  McGuinness and completed initial draft ISO KIF
  metamodel 10/2003
• Learned that the ISO KIF draft was superceded by
  SCL, solicited help from Pat Hayes to understand
  SCL and assist in modeling
• Continued SCL modeling effort, iteratively and
  synergistically with the SCL development team
  11/2003
• Goals included focus on completeness
  (multiplicities, role names, OCL invariants),
  accuracy in language representation, minimalistic
  and intuitive XMI/XML
• Completed draft metamodel with SCL team approval
  1/2004
• Continued revision process as the SCL language
  was refined published SCL metamodel in draft
  ODM specification, 8/2004

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Phrases
7
Phrases

• Import, Sentence, and TextComment form a disjoint
  partition of Phrase
• context SCLPhrase inv XOR
• (self.oclIsKindOf(SCLImports) xor
  self.oclIsKindOf(Sentence)) and
• (self.oclIsKindOf(Imports) self.oclIsKindOf(Tex
  tComment)) and
• (self.oclIsKindOf(Sentence) xor
  self.oclIsKindOf(TextComment))

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Expressions
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Terms
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Names and Terms

• The lexical syntax section of the SCL document
  has rules for what can be a valid name.
• Some of these rules cannot be expressed in OCL.
  For example
• name namesequence numeral quotedstring
  enclosedname
• which depends on preceding definitions of
  enclosedname, quotedstring, numeral and
  namesequence, where names that include white
  space or certain punctuation marks, quotation
  marks, etc. must be defined as enclosedname
• We can use OCL to rule out special names but not
  to state rules about what kinds of ascii
  characters are allowed. Enforcing these rules
  has to be the responsibility of the parser.
• The Name/CommentedTerm/ApplicationOfFunction
  partition is disjoint
• context Term inv DisjointPartion
• (self.oclIsKindOf(Name) xor self.oclIsKindOf(Com
  mentedTerm)) and
• (self.oclIsKindOf(Name) xor self.oclIsKindOf(App
  licationOfFunction)) and
• (self.oclIsKindOf(CommentedTerm) xor
  self.oclIsKindOf(ApplicationOfFunction))
• Note the lack of a simple disjoint declaration
  in MOF

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Atoms
12
Sentences
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Atoms and Sentences

• ApplicationOfRelation, RolePairSet, and Equation
  form a disjoint partition
• context Atom inv DisjointPartition
• (self.oclIsKindOf(ApplicationOfRelation) xor
  self.oclIsKindOf(RolePairSet)) and
• (self.oclIsKindOf(ApplicationOfRelation) xor
  self.oclIsKindOf(Equation)) and
• (self.oclIsKindOf(RolePairSet) xor
  self.oclIsKindOf(Equation))
• The partition formed by the subclasses of
  Sentence is disjoint
• context Sentence inv DisjointPartition
• (self.oclIsKindOf(and) xor self.oclIsKindOf(or))
  and
• (self.oclIsKindOf(and) xor self.oclIsKindOf(not
  )) and
• (self.oclIsKindOf(and) xor self.oclIsKindOf(imp
  lies)) and
• (self.oclIsKindOf(and) xor self.oclIsKindOf(iff
  )) and
• (self.oclIsKindOf(and) xor self.oclIsKindOf(for
  all)) and
• (self.oclIsKindOf(and) xor self.oclIsKindOf(exi
  sts)) and
• (self.oclIsKindOf(and) xor self.oclIsKindOf(Ato
  m)) and
• (self.oclIsKindOf(and) xor self.oclIsKindOf(Com
  mentedSentence)) and
• (self.oclIsKindOf(or) xor
  self.oclIsKindOf(not)) and
• (self.oclIsKindOf(or) xor
  self.oclIsKindOf(implies)) and

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Boolean (Logical) Sentences
15
Quantified Sentences
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Next Steps

• Examples, where each example consists of
• Sample SCL expressions in SCL textual syntax
• Corresponding abstract syntax trees as instances
  of the metamodel, expressed as object diagrams
• These kinds of examples were in the CWM
  specification and should be in all OMG metamodel
  specifications
• Inclusion of mappings from RDFS/OWL to SCL, with
  examples
• Examples of OWL ontologies expressed in the ODM
  and extended through SCL constraints, as might be
  input to an SCL reasoner
• Possible refinement of XMI via XMIs mapping
  parameters
• XMIs schema production rules are parameterized
• SCL XMI produced using defaults for all
  parameters
• Specification of compliance points