Section: New Results

Dynamic aspects of networks of ontologies

Huge quantities of data described by ontologies and linked together are made available. These are generated in an independent manner by autonomous providers such as individuals or companies. They are heterogeneous and their joint exploitation requires connecting them.

However, data and knowledge have to evolve facing changes in what they represent, changes in the context in which they are used and connections to new data and knowledge sources. As their production and exchange are growing larger and more connected, their evolution is not anymore compatible with manual curation and maintenance. We work towards their continuous evolution as it is critical to their sustainability.

Two different approaches are currently explored.

Evolution of ontology networks and linked data

Participants : Adam Sanchez Ayte [Correspondent] , Jérôme David, Jérôme Euzenat.

We are considering the global evolution of knowledge represented by interdependent ontologies, data, alignments and links. Our goal is to be able to maintain such a structure with respect to the processes which are involved in its construction: logical inference, ontology matching, link key extraction, link generation, etc.

Our initial work is focused on how data and ontology changes cause alignment evolution, in particular when the alignment have been produced through instance-based matching using links between data. In this regard, we are developing techniques for circumscribing the elements and relationships affected by the change as well as evaluating the need for change propagation, i.e, most of the time a simple change will not trigger link key recomputation (§ 7.2.3 ).

This work is part of the PhD thesis of Adam Sanchez Ayte developed in the Lindicle project (§ 9.1.1 ).

Revision in networks of ontologies

Participant : Jérôme Euzenat [Correspondent] .

We reconsidered the belief revision problem in the context of networks of ontologies (§ 3.2 ): given a set of ontologies connected by alignments, how to evolve them such that they account for new information. In networks of ontologies, inconsistency may come from two different sources: local inconsistency in a particular ontology or alignment, and global inconsistency between them. Belief revision is well-defined for dealing with ontologies; we have investigated how it can apply to networks of ontologies. We formulated revision postulates for alignments and networks of ontologies based on an abstraction of existing semantics of networks of ontologies. We showed that revision operators cannot be simply based on local revision operators on both ontologies and alignments. We adapted the partial meet revision framework to networks of ontologies and show that it indeed satisfies the revision postulates [7] . Finally, we considered strategies based on network characteristics for designing concrete revision operators.