An inferred view of a concept definition that includes only defining relationships that are necessarily true.

Notes

• The necessary normal form is designed to represent an inferred view derived from the enhanced concept definitions in a form that can be distributed in the relationship file.  Although the enhanced features cannot be fully represented within the structure of the relationship file, the necessary normal form provides a view of the results of classifying data that is accessible to those without access to description logic tools.

Change Notices

• Changes introduced in the July 2018 release of the International Edition, enhanced the ability of SNOMED CT to support more advanced description logic. These changes allow the stated view of concept definitions to use axioms represent using the OWL Functional Syntax.

Alternatives

• NNF

Related Links

• Generating Necessary Normal Form relationships from the OWL refsets