Entity (Node)

Entities as Nodes in a Knowledge Graph

In the context of a standard knowledge graph, an entity is a fundamental component that represents a real-world object, event, situation, or abstract concept. These entities are the nodes of the graph structure. They are the 'things' about which information is stored and interconnected.

Examples of entities can range from concrete objects like 'the Eiffel Tower' or 'IBM', to abstract concepts such as 'love' or 'customer relationship'. Each entity is typically unique and serves as a point of reference within the network of knowledge.

Entities in the Perseus Client

An Entity in the Perseus Client directly corresponds to a node in a knowledge graph. It represents a distinct "thing" or concept, such as a person, a company, a product, or a location.

Each Entity is classified by its type (e.g., Person, Company), which acts as a label for the node, and possesses a unique identifier. Entities are the subjects and objects in the factual statements (triples) that form the graph.

Entity Properties

An Entity also contains properties, which are key-value pairs that provide detailed attributes about the entity. These properties are represented by LiteralValue objects and correspond to the properties field in the Entity model.

For example, an entity representing an award would have properties defining its name.

Example of an Entity Object

Here is an example of what an Entity object for the "Nobel Prize in Physics" might look like in the Perseus Client.

Entity(
    uri="http://example.com/award/NobelPrizeInPhysics",
    types=["http://example.com/ontology/Award"],
    properties={
        "http://www.w3.org/2000/01/rdf-schema#label": LiteralValue(value="Nobel Prize in Physics")
    },
)