KARMA is a prototypical implementation of a combined approach to answering conjunctive queries over ontologies specified in the DL ELHO.
Given an ELHO ontology, an ABox, and a conjunctive query, KARMA computes the answers to the query over the ontology plus the data using a three-step process:
The third step is necessary because, to ensure termination, the datalog program computed in the first step is not equivalent to the given ontology and it may imply facts that do not follow from the ontology and the data; however, this is done in a way that allows for the third step.
KARMA is open-source and released under LGPL. The system and the evaluation data is included in the downloaded zip file.
Currently, KARMA is only available with a command-line interface.
Giorgio Stefanoni, Boris Motik, and Ian Horrocks. Introducing Nominals to the Combined Query Answering Approaches for EL. AAAI 2013. To appear.