LogosLink User's Manual · LogosLink version 2.0.0.2

Centrality Analytics (Ontology)

Centrality analytics shows what entities in an ontology are more connected to others, that is, are more central.

This is useful to estimate the relative importance or relevance of different entities in the ontology.

Parameters

(none)

Results

Results are given as a set of lists and tree tables, one for the entities themselves, and one for each kind of applicable element in the embedded context, if any.

Entities

The list shows the entities in the ontology, plus some details for each one.

For each entity, the following data are shown:

Key, Identifier and Name. These show the main details of the entity.
Super. This is the number of super-types of the entity.
Sub. This is the number of sub-types of the entity.
Super+Sub. This is the number of super-types plus sub-types of the entity.
Relative. This is the super-type plus sub-type centrality of the entity, relative to the theoretical maximum. See the Details section for more information.
Types. This is the number of types of the entity.
Instances. This is the number of instances of the entity.
Types+Instances. This is the number of types plus instances of the entity.
Relative. This is the types and instances centrality of the entity, relative to the theoretical maximum. See the Details section for more information.
Connections. This is the number of connections of the entity.
Relative. This is the connection centrality of the entity, relative to the theoretical maximum. See the Details section for more information.
References. This is the number of references of the entity.
Relative. This is the reference centrality of the entity, relative to the theoretical maximum. See the Details section for more information.
Overall. This is the sum of the numbers of super-types, sub-types, types, instances, references and connections of the entity.
Relative. This is the overall centrality of the entity, relative to the theoretical maximum. See the Details section for more information.

Linked Themes

The tree table shows the themes in the embedded context, plus some details for each one.

For each theme, the following data are shown:

Centrality. This is the average overall centrality of the entities linked to the theme.

Linked Positions

The tree table shows the positions in the embedded context, organised by theme, plus some details for each one.

For each position, the following data are shown:

Centrality. This is the average overall centrality of the entities linked to the position.

Linked Agents

The tree table shows the agents in the embedded context, organised by theme, plus some details for each one.

For each agent, the following data are shown:

Centrality. This is the average overall centrality of the entities linked to the agent.

Details

Relative centralities are calculated by dividing the relevant absolute number by a theoretical maximum. For example, the relative references centrality is calculated by dividing the number of references of the entity between the theoretical canonical maximum number of references that an entity may have in the ontology.

Theoretical canonical maxima are determined as follows:

For super- and sub-types. The maximum is the number of categories in the ontology minus 1.
For types and instances. The maximum is the number of entities in the ontology minus 1.
For connections. The maximum is the number of categories in the ontology minus 1.
For references. The maximum is the number of entities in the ontology minus 1.
For overall. The maximum is the number of entities in the ontology minus 1.

In this manner, a relative centrality of 0% indicates that the entity is not connected at all (i.e. is not central at all). A relative centrality of 100% indicates that the entity is fully connected to all other entities (i.e. is at the centre of the ontology).

In some cases, super-centrality may occur, for which the relative measure is greater than 100%. This happens when an entity has multiple connections to another one.