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Difference between revisions of "Negation Sources"
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* [https://confluence.ihtsdotools.org/display/DOC/ SNOMED CT Technical Implementation Guide]: see 7.8.2.4.7 Retrieving absent findings | * [https://confluence.ihtsdotools.org/display/DOC/ SNOMED CT Technical Implementation Guide]: see 7.8.2.4.7 Retrieving absent findings | ||
** This section discusses how negation changes the rules for subsumption testing. The solution is to reverse the candidate/predicate relation for Situation with Explicit Context findings using "known absent" or a descendant. | ** This section discusses how negation changes the rules for subsumption testing. The solution is to reverse the candidate/predicate relation for Situation with Explicit Context findings using "known absent" or a descendant. | ||
| − | ** | + | ** Note that this approach assumes a pattern of Procedure with explicit context. The pattern of an Observable with value "absent" is not addressed. |
| + | ** This approach can probably be generalized. | ||
Revision as of 16:59, 16 June 2016
Back to Negation Requirements
- Alan Rector, What's in a Code?
- On separation of ontology from terminology & use of "situation" construct to harmonize positive & negative assertions
- Alan Rector, Negation & Null Values (rough notes)
- On preference for "absent" to "negation," at least at first
- SNOMED CT Technical Implementation Guide: see 7.8.2.4.7 Retrieving absent findings
- This section discusses how negation changes the rules for subsumption testing. The solution is to reverse the candidate/predicate relation for Situation with Explicit Context findings using "known absent" or a descendant.
- Note that this approach assumes a pattern of Procedure with explicit context. The pattern of an Observable with value "absent" is not addressed.
- This approach can probably be generalized.
