Partitioning the Semantic Network of the UMLS.
Year: 2000
Type: article
Abstract: The Unified Medical Language System (UMLS) relationship will be a root of its semantic-type combines many well established medical informatgroup. Most, but not all, semantic-type groups ics terminologies into a unified knowledge reprehave unique roots. If a semantic-type group has sentation system. However, the UMLS's enora unique root, then all other semantic types in mous size and complexity [730,000 concepts in the the group are its descendants. Taken altogether, Metathesaurus (META)] can pose serious comprethe semantic-type groups of the SN form a partihension problems for potential users. The UMLS's tion. The SN is partitioned into 71 semantic-type Semantic Network (SN) helps to orient users to the groups. Of these, 47 contain just one semantic vast knowledge content of META. It is composed type. (We call such groups of a set of 134 semantic types which define highFor a partition to be effective, the groups of selevel abstractions for sets of concepts from META. mantic types have to be uniform not just in their Overall, the semantic types are arranged in a hierstructure but also in their semantics. For a group archy of IS-A relationships. In addition, there are of semantic types to be semantically uniform, it 54 kinds of (semantic) relationships which connect should have a unique root. The semantic uniforsemantic types. However, the SN abstract view mity is derived from the fact that each one of the of META can still be too large and difficult for semantic types in the group is a specialization of comprehension. the unique root. Most semantic-type groups have We concentrate on providing comprehensible unique roots. This phenomenon shows that uniaccess to the SN through simpler, more compact form groups tend to be semantically univiews. Specifically, we present a technique for parform most of the time, but not all the time. Since titioning the SN based on its relationship configusemantic uniformity is more important for comration. The outcome of our technique is a new, prehension than structural uniformity, we will now higher-level abstraction composed of sets of seprovide three rules to convert the structural parmantic types, called semantic-type groups. Contitioning into an enhanced semantic partitioning. sidering some enhancements leads to a revised The enhanced partition that emerges from apmethodology that partitions the SN into metaplying our rules to the structural partition will semantic types, a powerful viewing mechanism for be based on meta-semantic types. Each metathe SN and, in turn, META. semantic type is an abstract conceptual entity repOur partitioning technique is based on the disresenting a set of semantic types in the SN. Each tribution of the relationships (other than IS-A) will have a unique root semantic type and will thus among the semantic types of the SN. A relationbe semantically uniform. When a meta-semantic ship is introduced at a given semantic type and type is also a semantic-type group, it will be strucinherited by all its descendants (unless the inherturally uniform. Otherwise, it will have approxiitance is interrupted by the DNI designation or mate structural uniformity. blocking). The focus is placed on the relationRule 1: Each semantic-type group with a unique ships because of their overall definitional imporroot becomes a meta-semantic type. O tance. In fact, we define the structure of a seThe next rule deals with semantic types mantic type as the set of its defined relationships, which are semantic types without children. whether they be introduced directly or inherited. Rule 2: If a leaf semantic type L is in a singleton Two semantic types are structurally similar if in the structural partition, then it is added to the they both have the exact same set of relationships meta-semantic type which contains its parent. 0 defined for them. The identical nature of their reRule 3: Let the semantic types Al, A2,*An lationship implies that they bear a close (n > 2) be roots of the same semantic-type group resemblance in meaning. It is therefore justified of the structural partitioning. Add them all to to group them together along that dimension of the meta-semantic type of their lowest common similarity to form a higher-level abstraction: ancestor in the IS-A hierarchy. O Definition (Semantic-type group): A The enhanced partition of the entire SN consemantic-type group is an abstract conceptual entains 28 meta-semantic types. Two of them are tity comprising the set of all semantic types with singletons. (As we see, the technique does not the exact same set of relationships. 0 eliminate all singletons.) Definition (Root of a semantic-type In conclusion: we have introduced a technique group): A semantic type is a root of a semanticfor partitioning the SN into a collection of highertype group if none of its parents belongs to the level conceptual entities to facilitate orientation. semantic-type group. 0 Clearly, a semantic type which introduces a new
Source: Europe PMC (PubMed Central)
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W1649659531