Umeå universitets logga

In Virtual Knowledge Graphs (VKGs), access to a relational data source is provided through an ontology, which is linked to the data source via declarative mappings. VKGs stand as a predominant paradigm for the access to (and integration of) heterogeneous data sources. However, little attention has been paid so far to the issue of updates in VKGs expressed over the ontology, which represents a crucial feature for fully managing data sources through the lens of an ontology. In this paper, we consider the problem of updating a VKG instance by specifying a set of insertions and deletions of ontology instances and propagating these updates to the underlying data source through the VKG mapping. We consider ontologies specified in the DL-LiteR lightweight ontology language and study the problem for the case where source queries in mappings are unions of conjunctive queries. We rely on the notion of maximum recovery of VKG mappings, borrowed from the data exchange setting, and propose methods to compute the set of source updates that translate an ontology update with a minimal side-effect, considering both insertions and deletions of multiple ABox assertions.