A set of nodes connected to one another by lines (edges) in which each connection has a specified direction such that no route that follows the direction of the connections enters a loop (cycle).

Notes

• The 

  Gloss
  Space true t SNOMED CT

   

  Gloss
  t subtype hierarchy

   is a Directed Acyclic Graph. 

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  t SNOMED CT concepts

   are nodes and 

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  t subtype relationships

   are the directed lines that connect them. All 

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  t subtype relationships

   lead from a more specific 

  Gloss
  t concept

   to a more general 

  Gloss
  t concept

  , so a cycle would be a logical error (e.g. if "rubella virus" is a type of "virus" and "virus" is a type of "microorganism", then "microorganism" cannot be a type of "rubella virus").

Illustrative Example - Directed Acyclic Graph 

Alternatives

• DAG

Related Links

• Wikipedia
  • Directed Acyclic Graph