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Creating a Transitive Closure File

SNOMED International provide provides a Perl script that reads the snapshot relationships file. By processing this file, it rapidly generates the transitive closure of all the subtype relationships and then saves this as a file. The result a two column file (subtypeId and supertypeId) containing more than 6.5 million rows. This transitive closure file can then be read into a database table in the same way as the release files.

Using a Transitive Closure File

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• Test is concept A is a subtype of concept B
• List all supertypes of concept A
• List all subtype subtypes of concept A.

Computing Proximal Primitive Supertypes

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1. Use the transitive closure table to get the set of all concepts that are supertypes of concept A
   • Call this set: Set-B
2. Create a subset of Set-B containing only those concepts with definitionStatusId=

   Concept
   t 900000000000074008 |

   primitive

   Primitive|

    
   
   • Call this set: Set-C

3. Create a subset of Set-C containing only those concepts that have no subtypes that are also in Set-C

   Footnote Macro
   Concepts in Set-C that also have subtypes in Set-C are primitive supertypes of concept A but they are not proximal primitive supertypes because these subtype(s) are are more specific concepts that are also primitive supertypes of concept A.

   • The resulting set represents the primitive supertypes of concept A.

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