Jaroslaw Bak

Usage of the Jess Engine, Rules and Ontology to Query a Relational Database

We present a prototypical implementation of a library tool, the Semantic Data Library (SDL), which integrates the Jess (Java Expert System Shell) engine, rules and ontology to query a relational database. The tool extends functionalities of previous OWL2Jess with SWRL implementations and takes full advantage of the Jess engine, by separating forward and backward reasoning. The optimization of integration of all these technologies is an advancement over previous tools. We discuss the complexity of the query algorithm. As a demonstration of capability of the SDL library, we execute queries using crime ontology which is being developed in the Polish PPBW project.

Extended rules in knowledge-based data access

We present a method for an efficient knowledge-based access to relational data. Knowledge is represented as a set of rules (basic rules) and describes a source data at concept (ontological) level. Forward chaining in the integrated system is performed with extended rules, which are obtained by a goal- and dependency-directed transformation of the basic rules. The novel feature of our method is generality - every rule is generated so that includes all possible binding of the head predicates, and variable dependencies, while in many implementations of the magic method the succession of bindings depends on a query. We demonstrate a query answering algorithm and our prototypical implementation of the system coupled with the Jess engine. The results of performance evaluation are presented and compared to the results described in our previous works.

RuQAR: Reasoning Framework for OWL 2 RL Ontologies

This paper addresses the first release of the Rule-based Query Answering and Reasoning framework (RuQAR). The tool provides the ABox reasoning and query answering with OWL 2 RL ontologies executed by forward chaining rule reasoners. We describe current implementation and an experimental evaluation of RuQAR by performing reasoning on the number of benchmark ontologies. Additionally, we compare obtained results with inferences provided by HermiT and Pellet. The evaluation shows that we can perform the ABox reasoning with considerably better performance than DL-based reasoners.

Rule-Based Reasoning System for OWL 2 RL Ontologies

In this paper we present a method of transforming OWL 2 ontologies into a set of rules which can be used in a forward chaining rule engine. We use HermiT reasoner to perform the TBox reasoning and to produce classified form of an ontology. The ontology is automatically transformed into a set of Abstract Syntax of Rules and Facts. Then, it can be transformed into any forward chaining reasoning engine. We present an implementation of our method using two engines: Jess and Drools. We evaluate our approach by performing the ABox reasoning on the number of benchmark ontologies. Additionally, we compare obtained results with inferences provided by the HermiT reasoner. The evaluation shows that we can perform the ABox reasoning with considerably better performance than HermiT. We describe the details of our approach as well as future research and development.