Joachim Kröger

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With the substantial change of declarative query languages from plain SQL to the so called object SQLs in particular OQL there has surprisingly been not much change in the way problems of query re presentation and optimization for such languages are tackled We identify some of the di culties pure algebraic approaches experience when fac ing object models(More)
Examples of a combined approach using in vivo as well as in vitro methods for the assessment of prenatal toxicity are presented. The topics discussed include the analysis of the possible embryotoxic potential of valproic acid (VPA), female sex hormones, bis(tri-n-butyltin) oxide (TBTO), and acyclovir and the problem of supplementing in vitro systems with(More)
This paper describes some concepts for the evaluation and optimization of ODMG-OQL queries. We present a logical object algebra for the internal representation of OQL queries. Diierent optimization techniques are sketched: factorization of common subexpressions, dependency-based optimization, and query rewriting. Afterwards, our physical algebra is(More)
In dieser Rubrik wird über die im deutschsprachigen Raum abgeschlossenen Dissertationen berichtet. Dissertationen sind ein typischer Ausdruck für die auf einem Fachgebiet aktuellen Forschungsund Entwicklungsthemen. Um eine einheitliche Darstellung zu erreichen, wird jeweils folgende Information angegeben: Thema, Autor, Universität, Jahr, Gutachter und(More)