The faceted browsing of individuals is the operation that aims to establish groups of individuals according to certain criteria. For example, the facet “20th Century German writers” is a group of individuals from the “physical person” category who have “writer” as their profession and who were born in the 20th Century. This type of grouping can be expressed with the support of OWL2 expressions and implemented in the system in the form of a tree of restrictions. The reasoning engine goes along this tree to extract the individuals who respond to the different constraints expressed in the restriction.
A facet is always stored in the triplestore in the form of a logical expression and has no permanent attachment to the individuals that it contains. These individuals are dynamically added and deleted as a function of the conformity of their properties to the conditions required by this facet.
An individual’s range
A local individual is an instance that is created locally, at the heart of an analysis, in a given context (e.g. the context of a segment). It can be reused and enriched in other local contexts belonging to the same analysis. Different properties can thus be associated with it according to its different contexts of use.
A media individual is an instance that is created in its own graph (initial context) and can be reused in the different analyses of this medium. The initial context includes information that will be valuable for any possible use of this individual. The reuse of the individual consists of defining or adding certain properties that will only be useful in the new context of use. This individual can be searched and found by the reasoner with the help of SPARQL queries and can be deleted if it is not a reference in any other context.
The third category of individuals is that of shared entities. Like for media individuals, a shared entity has its own graph where the information able to be shared by several documents is inserted. It can be found with the help of SPARQL queries and reused (contextualized) several times to describe the different media stored in the database.
An individual can be promoted from one category to another. For example, the user can start by creating a local individual within a given segment. This individual is reused several times within the same analysis, in different segments. In the course of his documentation work, the user realizes that this individual is starting to play a central role in the medium analyzed. He then decides to promote it as a media individual so as to be able to reuse it in other analyses of the same medium. Then, by working on other documents, he realizes that this same individual from the real world is referenced in the form of doubles in other media. He then transforms his media individual into a shared entity and can thus use a single reference in the description of new documents or by recovering descriptions containing doubles.