Lexicon · Mathematical and computational foundations
Knowledge graph
Fully specified name: Knowledge graph (concept)
A representation connecting entities through explicit relationships.
- Scope note
- A graph organizes assertions without guaranteeing their truth.
- Synonyms
- None recorded as true synonyms in this context.
- Monograph
- Knowledge graphs (draft)
- External mappings
- None recorded. In W0 no mapping to SNOMED CT® or any external authority is asserted for this entry. A future mapping record will carry source system, identifier, version, relation type, evidence, author, confidence where meaningful, and review state.
- Formal status
- Editorial entry only. It is not part of any released ontology and a prose edit here changes no formal definition.
Draft. This entry is an unreviewed draft. Its sources have not been checked by a named person and no domain reviewer has approved it. Treat every claim as provisional.
Notes
A knowledge graph stores entities as nodes and relationships as labeled, directed edges, and makes the result queryable. The phrase became common after 2012, when large search companies used it for their entity databases, and it is now used for anything from a small research dataset to a corporate integration layer. What distinguishes a knowledge graph from a database table is that the relationships are first-class and explicit; what distinguishes it from an Ontology is that a graph is mostly assertions about individuals, while an ontology is mostly definitions of classes and the rules that govern them. Many knowledge graphs use an ontology as their schema.
The scope note is the caution a physician or scientist most needs. A graph records that someone asserted an edge. It does not establish that the edge is true, that it was measured in a relevant system, or that it is still current. Two graphs built from the same literature by different extraction methods will disagree. Without Provenance on each edge the reader cannot tell a curated assertion from an automatically mined one. The standard model for expressing such graphs on the web is RDF (Resource Description Framework); the monograph examines what graphs make possible and what they leave to interpretation.