Publications in Scientific Journals:
R. Pichler, E. Sallinger, V. Savenkov:
"Relaxed Notions of Schema Mapping Equivalence Revisited";
Theory of Computing Systems (invited),
52
(2013),
3;
483
- 541.
English abstract:
Recently, two relaxed notions of equivalence of schema mappings have been introduced, which provide more potential of optimizing schema mappings than logical equivalence: data exchange (DE) equivalence and conjunctive query (CQ) equivalence. In this work, we systematically investigate these notions of equivalence for mappings consisting of s-t tgds and target egds and/or target tgds. We prove that both CQ- and DE-equivalence are undecidable and so are some important optimization tasks (like detecting if some dependency is redundant). However, we also identify an important difference between the two notions of equivalence: CQ-equivalence remains undecidable even if the schema mappings consist of s-t tgds and target dependencies in the form of key dependencies only. In contrast, DE-equivalence is decidable for schema mappings with s-t tgds and target dependencies in the form of functional and inclusion dependencies with terminating chase property.
Keywords:
Schema mappings, Schema mapping equivalence, Data translation, Data exchange, Data integration
"Official" electronic version of the publication (accessed through its Digital Object Identifier - DOI)
http://dx.doi.org/10.1007/s00224-012-9397-0
Electronic version of the publication:
http://link.springer.com/article/10.1007%2Fs00224-012-9397-0
Related Projects:
Project Head Reinhard Pichler:
Service-orientierte Datenintegration
Created from the Publication Database of the Vienna University of Technology.