SKOS Ecoterm 2006 Alistair Miles CCLRC Rutherford Appleton Laboratory

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SKOSEcoterm 2006Alistair MilesCCLRC
Rutherford Appleton Laboratory
Semantic Web Best Practices and Deployment
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Reminder what is it?

• Simple Knowledge Organisation System
• Formal language for representing controlled
  structured vocabularies (thesauri, classification
  schemes, ?)
• Subject metadata information retrieval
• this document is about romantic love.
• this document is about the cure of tuberculosis
  by x-ray in India in the 1950s.
• Application of RDF

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Since Ecoterm 2005

• SKOS Core Guide SKOS Core Vocabulary
  Specification
• First Working Draft May 2005
• Second Working Draft October 2005
• Minor changes
• Quick Guide to Publishing a Thesaurus on the
  Semantic Web
• First Working Draft May 2005

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What comes next ?

• Life after SWBPD-WG ?
• Plans for next phase of W3C Semantic Web Activity
  
• New WG?
• SKOS W3C Recommendation by end 2007?
• N.B. Not yet approved!

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If Rec then

• What is the scope? What is the fundamental design
  goal?
• First part of SKOS Rec would be requirements
  specification.
• Between now and Sept/Oct 2006 define scope and
  requirements.

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What Id like to do here

• Talk about some of the assumptions behind SKOS.
• Sketch some ideas on how to define scope and
  requirements for SKOS.
• Get your feedback.
• public-esw-thes_at_w3.org
• SKOS Requirements for Standardization
• isegserv.itd.rl.ac.uk/public/skos/press/dc2006/pap
  er.pdf

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Brief history of scope

• 2003-04 SWAD-Europe
• ISO 2788 thesauri
• Non-standard thesauri via extensibility e.g.
  GeMET
• Classification scheme (PACS)
• Multilingual thesauri
• Semantic mapping
• 2004 W3C Glossaries
• 2005 Discussion re terminologies
• Subject headings? Gazeteers? Folksonomies?
  Taxonomies?

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Assumptions purpose

• Formal representation of controlled structured
  vocabularies intended for use in information
  retrieval applications.

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Assumptions workflow

• Build a vocabulary
• Build an index
• Retrieve

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Assumptions components

• Vocabulary Development Application
• Something to help build a vocabulary
• Indexing Application
• Something to help build an index
• Retrieval Application
• Something to help retrieve things
• SKOS ultimately designed to support
  interoperation of these three key components.

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Proposed scope

• SKOS is a formal language for representing
  controlled structured vocabularies intended for
  use within information retrieval applications.
• SKOS is required to support the interoperation of
  these three key components.
• I.e. define the requirements for SKOS by
  describing a set of functionalities that must be
  enabled.

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Other components

• Vocabulary mapping ?
• Metadata registries ?
• ?

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Component specs

• first discuss social and technological context,
  then return to component specs

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Context

• What is the social and technological context in
  which controlled structured vocabs are used?
• Assume two basic needs
• Locate something I already know about.
• Discover something new.
• N.B. a good location service is not necessarily a
  good discovery service.
• Cf. Google and del.icio.us

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Strategies

• Basic strategies for implementing retrieval
  services
• Statistical text analysis
• Analysis of user behaviour
• Index with controlled vocab
• Other strategies
• kos-assisted text analysis?

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Cost problem

• Given that applying controlled structured vocab
  for retrieval involves significant initial and
  ongoing investment
• Given that other strategies are cheaper
• Huge pressure to drive down cost and increase
  utility.
• Requirement for seamless integration.
• I.e. controlled vocab is seldom used in
  isolation, most applications will combine
  strategies.

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Use case

• Search portal
• Use combined strategies.

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Component specs

• Important factors
• Minimise cost.
• Decentralisation.
• Assistance.
• Maximise utility.
• Query expansion.
• Smart ranking.
• Maximize lifetime.
• Use the Semantic Web!
• Situation A. search across many collections,
  where indexers use same controlled vocab.
• Situation B. search across many collections,
  where indexes use different controlled vocabs.

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Focus areas

• Decentralisation requires different models of
  collaboration and change.
• Representing change a key factor to keeping a
  vocab applicable.
• Ranking and scoring well understood for text,
  less so for controlled index.
• Theory of query expansion? Field trials of query
  expansion?
• Strategies for providing assistance?

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Change and collaboration

• Continuum of collaboration models centralized
  lt-gt decentralised
• Continuum of change management models continuous
  lt-gt discrete
• Decentralization can reduce cost of development
  and maintenance
• Change management can ensure continued utility
  maximize ROI
• Support for declarative representation of change
  a requirement for SKOS.

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Semantic Web architecture

• Exploit Semantic Web facility to distribute and
  merge data.
• However, publication of data in the Semantic Web,
  best practices need work.
• See Best Practice Recipes for Publishing RDF
  Vocabularies W3C Working Draft (Google
  publishing RDF).

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Semantic Web architecture
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Direct interaction
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Information retrieval

• Indexing and query evaluation well understood for
  text content.
• Less well understood for controlled metadata.
• Query types?
• Query evaluation strategies, e.g. query
  expansion?
• Ranking?

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Assistance for indexers

• Provide suggestions
• Comparison of labels and annotations
• Machine learning
• Exploit lexical resources
• ?

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Assistance for mappers

• Provide suggestions
• Analysis of labels and annotations
• Exploit lexical resources
• ?

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Summary

• SKOS fundamental requirement to support
  information retrieval using controlled structured
  vocabularies.
• Define requirements by describing information
  retrieval functionalities.
• Divide functionalities into
• Presentation styles
• Query types e.g. compound queries, coordination
• Query evaluation strategies
• Assumptions
• Key components
• Semantic Web interaction
• Context pressure to make vocabularies
  profitable
• Issues change, assistance, theory