arXiv subjects

Heike Stephan

Publications and source records attributed to Heike Stephan.

4 recordsLinked to original sources

arXiv2017

Bottom-Up Evaluation of Datalog: Preliminary Report

Bottom-up evaluation of Datalog has been studied for a long time, and is standard material in textbooks. However, if one actually wants to develop a deductive database system, it turns out that there are many implementation options. For instance, the sequence in which rule instances are applied is not given. In this paper, we study a method that immediately uses a derived tuple to derive more tuples (called the Push method). In this way, storage space for intermediate results can be reduced. The main contribution of our method is the way in which we minimize the copying of values at runtime, and do much work already at compile-time.

cs.DB↗

arXiv2017

Experiences with Some Benchmarks for Deductive Databases and Implementations of Bottom-Up Evaluation

OpenRuleBench is a large benchmark suite for rule engines, which includes deductive databases. We previously proposed a translation of Datalog to C++ based on a method that "pushes" derived tuples immediately to places where they are used. In this paper, we report performance results of various implementation variants of this method compared to XSB, YAP and DLV. We study only a fraction of the OpenRuleBench problems, but we give a quite detailed analysis of each such task and the factors which influence performance. The results not only show the potential of our method and implementation approach, but could be valuable for anybody implementing systems which should be able to execute tasks of the discussed types.

cs.DB↗

arXiv2014

A Variant of Earley Deduction With Partial Evaluation

We present an algorithm for query evaluation given a logic program consisting of function-free Datalog rules. It is based on Earley Deduction [4, 6] and uses a partial evaluation similar to the one we devel oped for our SLDMagic method [1]. With this, finite automata modeling the evaluation of given queries are generated. In certain cases, the new method is more efficient than SLDMagic and the standard Magic Set method since it can process several deduction steps as one.

cs.LO↗

arXiv2014

Application of Methods for Syntax Analysis of Context-Free Languages to Query Evaluation of Logic Programs

My research goal is to employ a parser generation algorithm based on the Earley parsing algorithm to the evaluation and compilation of queries to logic programs, especially to deductive databases. By means of partial deduction, from a query to a logic program a parameterized automaton is to be generated that models the evaluation of this query. This automaton can be compiled to executable code; thus we expect a speedup in runtime of query evaluation. An extended abstract/ full version of a paper accepted to be presented at the Doctoral Consortium of the 30th International Conference on Logic Programming (ICLP 2014), July 19-22, Vienna, Austria

cs.AI↗