Simplifying OWL

1
Simplifying OWL

• Learning lessons from Anaesthesia
• Nick Drummond

2
Overview

• IOTA
• Requirements
• Challenges
• Separating language from identity
• Referencing non-OWL resources
• Hiding complexity
• Optionality in OWL
• Conclusion

3
Guinea Pig - IOTA

• International Organisation for Terminology in
  Anaesthesia
• Part of the Anaesthesia Patient Safety Foundation
• 2 parallel efforts
• official feed of anaesthesia terms to SNOMED-CT
• Ontology required for AIMS systems

4
IOTA Tools

• Had DATAMS browser/editor
• Simple interface
• Completely designed for single task
• But
• Non standard solution no semantics defined
• Limited functionality
• Restricted support
• Not extensible
• Only 2 relationships (isa, hasa)

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Requirements

• Simple browsing/editing environment
• Standards for reuse
• Heavily concerned with language and references to
  external resources (for SNOMED)
• Simple structure but above and beyond
  sub/superclass (more properties wanted)

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OWL Subset

• Subsumption
• Primitive classes only (so far)
• Existential / Complement / Cardi restrictions
  (identified through competency questions)
• No complex fillers only Named Classes
• No disjoints (yet) likely to be added
  automatically
• Lots of annotations

7
Challenges

• Separating language from identity
• Referencing non-OWL resources
• Hiding complexity
• Optionality in OWL

8
Separating language from identity
vin
wine
plonk

• Resources are referred to by their URI
• rdfslabel or other properties can be used to
  hold the human-readable name
• IDs remain constant when renaming
• Can have multiple names (in different languages)
• Label string values less restricted (can use
  spaces etc)
• Can use the same label for multiple resources
  (disadvantage??)

9
Separating ID from language in Protege

• Meaningless IDs generated automatically
• conceptName is human readable
• Protégé supports idea of Browser Slot
• ie the property that is displayed to the user
• Extra search support needed

10
Referencing non-OWL resources

• owlseeAlso
• Have no URI to point to in SNOMED
• Create an individual in which to store any SNOMED
  info (such as name etc)
• Can be refactored later to point to the actual
  concept (if SNOMED ever published in OWL)

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Hiding Complexity

• Backward Es and upside-down As best left to the
  logicians
• Not all expressivity of OWL required
• eg simple fillers just named classes
• Currently no defined classes

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Disguising OWL

• Protégé forms are customisable
• forms design for purpose
• plugin form widgets
• Use min/max qualified cardinality
• Display compound restrictions

13
Using qualified cardinality and compound
restrictions
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Optionality

• Common requirement
• 2 use cases
• Reasoning using ontological knowledge an
  object may or may not have this feature
• Driving Forms using epistemic knowledge an
  object has this feature. The value may or not
  need to be specified

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Representing optionality in OWL

• No inbuilt notion in OWL
• Because of the open world assumption, possible to
  say anything about anything unless it has been
  explicitly discounted
• Several patterns, workarounds or botches
  could be subject in themselves
• We are considering a mixture to help make INTENT
  obvious and simple to manage but allow for
  CORRECT modelling in OWL

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Options (overview)

• State nothing (Open World)
• Using domain of property
• Use of possibly superproperty
• Universal/Existential restrs on inverse
• Reification
• Tool specific annotations
• Qualified Min Cardinality 0
• Define a subclass that has the property

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Defined Subclass
Person (some people own hats)
PersonThatOwnsAHat complete Person and owns
some Hat

• Hard to maintain
• Loses intent conceptually we are saying
  something about members of Person

• Ontologically correct
• Can infer membership / check consistency

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Min Cardi 0 (Qualified)

• QCRs standard in OWL1.1
• Means nothing to reasoners, but

• Captures intent
• matches our conceptual model and close to other
  representations relational models
• Simple to add/manage in OWL
• Easy to use as hints for GUI generation

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Transform

• Allow user to maintain intent ie min cardi
• Provide transform to create subclasses only WHEN
  REQUIRED
• Throw away when finished ? ?

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Conclusion

• IOTA have some common problems
• Many can be overcome even in OWL ?
• Open environments like Protégé can help create
  simpler interfaces
• General requirements found for Protégé-OWL