Quotation Kolaitis, Phokion, Pichler, Reinhard, Sallinger, Emanuel, Savenkov, Vadim. 2018. Limits of Schema Mappings. Theory of Computing Systems, 62, (4), 899-940.




Schema mappings have been extensively studied in the context of data exchange and data integration, where they have turned out to be the right level of abstraction for formalizing data inter-operability tasks. Up to now and for the most part, schema mappings have been studied as static objects, in the sense that each time the focus has been on a single schema mapping of interest or, in the case of composition, on a pair of schema mappings of interest. In this paper, we adopt a dynamic viewpoint and embark on a study of sequences of schema mappings and of the limiting behavior of such sequences. To this effect, we first introduce a natural notion of distance on sets of finite target instances that expresses how “close” two sets of target instances are as regards the certain answers of conjunctive que- ries on these sets. Using this notion of distance, we investigate pointwise limits and uniform limits of sequences of schema mappings, as well as the companion notions of pointwise Cauchy and uniformly Cauchy sequences of schema mappings. We obtain a number of results about the limits of sequences of GAV schema mappings and the limits of sequences of LAV schema mappings that reveal striking differences between these two classes of schema mappings. We also consider the completion of the metric space of sets of target instances and obtain concrete representations of limits of sequences of schema mappings in terms of generalized schema mappings, that is, schema mappings with infinite target instances as solutions to (finite) source instances.


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Publication's profile

Status of publication Published
Affiliation WU
Type of publication Journal article
Journal Theory of Computing Systems
Citation Index SCI
Language English
Title Limits of Schema Mappings
Volume 62
Number 4
Year 2018
Page from 899
Page to 940
DOI http://dx.doi.org/10.1007/s00224-017-9812-7
Open Access Y
Open Access Link https://link.springer.com/article/10.1007%2Fs00224-017-9812-7


SPARQL Evaluations and Extensions (kurz: SEE): Subproject XSPARQL, SPARQL Update & Linked Data
Savenkov, Vadim (Former researcher)
Kolaitis, Phokion (USCS, United States/USA)
Pichler, Reinhard (TU Wien, Austria)
Sallinger, Emanuel (Oxford University, United Kingdom)
Institute for Data, Process and Knowledge Management (AE Polleres) (Details)
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