Materialization Calculus for Contexts in the Semantic Web

Representation of context dependent knowledge in the Semantic Web
is becoming a recognized issue and a number of DL-based formalisms have been
proposed in this regard: among them, in our previous works we introduced the
Contextualized Knowledge Repository (CKR) framework. In CKR, contexts are
organized hierarchically according to a broader-narrower relation and knowledge
propagation across contexts is limited among contexts hierarchically related. In
several applications, however, this structure is too restrictive, as they demand
for a more flexible and scalable framework for representing and reasoning about
contextual knowledge.
In this work we present an evolution of the original CKR (based on OWL RL),
where contexts can be organized in any graph based structure (declared as a metaknowledge
base) and knowledge propagation is allowed among any pair of contexts
via a new ”evaluate-in-context” operator. In particular, we detail a materialization
calculus for reasoning over the revised CKR framework and prove its
soundness and completeness. Moreover, we outline the current implementation of
the calculus on top of SPRINGLES, an extension of standard RDF triple stores
for representing and rule-based inferencing over multiple RDF named graphs.