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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

The transitive closure can also be used to determine which supertype concept or concepts are essential to the definition of a concept. These concepts are known as the the 

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 definitionsStatusIddefinitionStatusId=

   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

   in Set C 

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

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

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