An enriched unified medical language system semantic network with a multiple subsumption hierarchy
- PMID: 14764611
- PMCID: PMC400518
- DOI: 10.1197/jamia.M1269
An enriched unified medical language system semantic network with a multiple subsumption hierarchy
Abstract
Objective: The Unified Medical Language System's (UMLS's) Semantic Network's (SN's) two-tree structure is restrictive because it does not allow a semantic type to be a specialization of several other semantic types. In this article, the SN is expanded into a multiple subsumption structure with a directed acyclic graph (DAG) IS-A hierarchy, allowing a semantic type to have multiple parents. New viable IS-A links are added as warranted.
Design: Two methodologies are presented to identify and add new viable IS-A links. The first methodology is based on imposing the characteristic of connectivity on a previously presented partition of the SN. Four transformations are provided to find viable IS-A links in the process of converting the partition's disconnected groups into connected ones. The second methodology identifies new IS-A links through a string matching process involving names and definitions of various semantic types in the SN. A domain expert is needed to review all the results to determine the validity of the new IS-A links.
Results: Nineteen new IS-A links are added to the SN, and four new semantic types are also created to support the multiple subsumption framework. The resulting network, called the Enriched Semantic Network (ESN), exhibits a DAG-structured hierarchy. A partition of the ESN containing 19 connected groups is also derived.
Conclusion: The ESN is an expanded abstraction of the UMLS compared with the original SN. Its multiple subsumption hierarchy can accommodate semantic types with multiple parents. Its representation thus provides direct access to a broader range of subsumption knowledge.
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References
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- US Department of Health and Human Services, National Institutes of Health, National Library of Medicine. Washington, DC: Unified Medical Language System (UMLS), 2003.
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- McCray AT, Hole WT. The scope and structure of the first version of the UMLS Semantic Network. Proc Annu Symp Comput Appl Med Care. 1990:126–30.
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- McCray AT. Representing biomedical knowledge in the UMLS Semantic Network. In: Broering NC, (ed). High-Performance Medical Libraries: Advances in Information Management for the Virtual Era. Westport, CT: Mekler, 1993, pp. 45–55.
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