Title
Constant Delay Enumeration with FPT-Preprocessing for Conjunctive Queries of Bounded Submodular Width.
Abstract
Marx (STOC~2010, J.~ACM 2013) introduced the notion of submodular width of a conjunctive query (CQ) and showed that for any class $\Phi$ of Boolean CQs of bounded submodular width, the model-checking problem for $\Phi$ on the class of all finite structures is fixed-parameter tractable (FPT). Note that for non-Boolean queries, the size of the query result may be far too large to be computed entirely within FPT time. We investigate the free-connex variant of submodular width and generalise Marx's result to non-Boolean queries as follows: For every class $\Phi$ of CQs of bounded free-connex submodular width, within FPT-preprocessing time we can build a data structure that allows to enumerate, without repetition and with constant delay, all tuples of the query result. Our proof builds upon Marx's splitting routine to decompose the query result into a union of results; but we have to tackle the additional technical difficulty to ensure that these can be enumerated efficiently.
Year
DOI
Venue
2019
10.4230/LIPIcs.MFCS.2019.58
MFCS
DocType
ISSN
Citations 
Conference
Proceedings of the 44th International Symposium on Mathematical Foundations of Computer Science, pp. 58:1-58:15, 2019
0
PageRank 
References 
Authors
0.34
0
2
Name
Order
Citations
PageRank
Christoph Berkholz1497.03
Nicole Schweikardt252637.82