Topic map

A topic map is a standard for the representation and interchange of knowledge, with an emphasis on the findability of information.

However, the developers quickly realized that with a little additional generalization, they could create a meta-model with potentially far wider application.

Topic maps are a form of semantic web technology similar to RDF.

The work standardizing topic maps (ISO/IEC 13250) took place under the umbrella of the ISO/IEC JTC 1/SC 34/WG 3 committee (ISO/IEC Joint Technical Committee 1, Subcommittee 34, Working Group 3 – Document description and processing languages – Information Association).

Names, resources, and relationships are said to be characteristics of abstract subjects, which are called topics.

With this in mind, work has gone into defining a standardized syntax for querying topic maps: It can also be desirable to define a set of constraints that can be used to guarantee or check the semantic validity of topic maps data for a particular domain.

Constraints can be used to define things like 'every document needs an author' or 'all managers must be human'.

[citation needed] The semantic expressive power of Topic Maps is, in many ways, equivalent to that of RDF,[citation needed] but the major differences are that Topic Maps (i) provide a higher level of semantic abstraction (providing a template of topics, associations and occurrences, while RDF only provides a template of two arguments linked by one relationship) and (hence) (ii) allow n-ary relationships (hypergraphs) between any number of nodes, while RDF is limited to triplets.