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Approach to building ontologies

Approach to building ontologies. A high-level view Chris Wroe. Introduction. Describe key steps in our approach Illustrate with a case study Not a discussion of project management Help inform integration of DL ontology building into wider knowledge base projects. Key steps.

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Approach to building ontologies

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  1. Approach to building ontologies A high-level view Chris Wroe

  2. Introduction • Describe key steps in our approach • Illustrate with a case study • Not a discussion of project management • Help inform integration of DL ontology building into wider knowledge base projects

  3. Key steps • Requirements gathering • Content scoping • Reusing existing components • Construction • Internal testing • Delivery • Evaluation

  4. Requirements gathering • What can a DL based ontology offer and should I use one? • Most people hold misconceptions • Key functions • Organising/ maintaining a large vocabulary within a knowledge base • Integrating vocabularies from several knowledge bases Requirements Scoping Reuse Construction Testing Delivery Evaluation

  5. Case study – a Drug Ontology • Research group builds a knowledge base of prescribing guidelines for specific conditions • KB excludes prescribing ‘common sense’ information. • E.g. ‘Don’t suggest a drug if it will interact with patient’s medication or other conditions’. • Need additional knowledge bases to hold • General drug interactions • General contraindications Requirements Scoping Reuse Construction Testing Delivery Evaluation

  6. Drug Ontology case study - requirements • Require a single vocabulary to integrate the information in each KB in a logically consistent way to support inference • Problems which DL ontologies can address • Vocabulary will be large (1000’s of terms) • Hard to maintain consistently by hand. • Concepts cover a wide range of granularity • Need to be organised in a classification • Concepts are complex • Multiple ways of classifying the same concept Requirements Scoping Reuse Construction Testing Delivery Evaluation

  7. Content scoping • Description Logic Ontology building is descriptive! • Focus taken away from enumeration and manual classification • Determine expected coverage and complexity of concept descriptions required. Requirements Scoping Reuse Construction Testing Delivery Evaluation

  8. Drug Ontology case study - scoping • Sample concepts from each knowledge base. • guideline KB– • if on anti-anginal … • Anti-aginal definition will need to include clinical condition concepts in definition (angina). • Angina definitions will need to include anatomy and physiology concepts in definition (heart, blood flow) Requirements Scoping Reuse Construction Testing Delivery Evaluation

  9. Reusing existing components • Reuse as much as possible especially at the higher levels of the ontology. • Standard upper level ontology • Previously built domain ontologies • Make what you build reusable Requirements Scoping Reuse Construction Testing Delivery Evaluation

  10. Drug Ontology case study - components • Upper level ontology reused • Anatomy and physiology domain ontologies reused and amended. Requirements Scoping Reuse Construction Testing Delivery Evaluation

  11. Construction • Often split into two tasks • Terminology knowledge acquisition • Interacting with domain experts • Terminology knowledge low-level modelling • Expressing knowledge in formal and consistent manner • Use a suite of design patterns and methodologies Requirements Scoping Reuse Construction Testing Delivery Evaluation

  12. Drug Ontology case study – knowledge acquisition • Use an intermediate representation • Simpler, less constrained • Customised to a domain • Authoring tools Requirements Scoping Reuse Construction Testing Delivery Evaluation

  13. Internal testing • What does the logic give you? • Logical consistency checked automatically • Semantic consistency can be assisted by the DL reasoner • By classification – miss-classification • Additional tools • By query and visualisation – missed classification Requirements Scoping Reuse Construction Testing Delivery Evaluation

  14. Case study – internal testing • Pain classed as a nervous system disease • Incorrect definition of pain Requirements Scoping Reuse Construction Testing Delivery Evaluation

  15. Evaluation • Testing of ontology within final application. • Case study - evaluation • Problem integrating existing vocabularies. • Meaning cannot be taken on face value • No human to intervene • Must also explicitly take into account context is which term is used. • Reference material versus Patient record Requirements Scoping Reuse Construction Testing Delivery Evaluation

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