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» Weighted Hypertree Decompositions and Optimal Query Plans
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PODS
2004
ACM
100views Database» more  PODS 2004»
14 years 11 months ago
Weighted Hypertree Decompositions and Optimal Query Plans
Francesco Scarcello, Gianluigi Greco, Nicola Leone
PODS
2007
ACM
159views Database» more  PODS 2007»
14 years 11 months ago
Generalized hypertree decompositions: np-hardness and tractable variants
The generalized hypertree width GHW(H) of a hypergraph H is a measure of its cyclicity. Classes of conjunctive queries or constraint satisfaction problems whose associated hypergr...
Georg Gottlob, Thomas Schwentick, Zoltán Mi...
CONSTRAINTS
2011
13 years 2 months ago
CP and IP approaches to cancer radiotherapy delivery optimization
Abstract. We consider the problem of decomposing an integer matrix into a positively weighted sum of binary matrices that have the consecutive-ones property. This problem is well-k...
Davaatseren Baatar, Natashia Boland, Sebastian Bra...
EDBT
2006
ACM
121views Database» more  EDBT 2006»
14 years 11 months ago
A Decomposition-Based Probabilistic Framework for Estimating the Selectivity of XML Twig Queries
In this paper we present a novel approach for estimating the selectivity of XML twig queries. Such a technique is useful for approximate query answering as well as for determining...
Chao Wang, Srinivasan Parthasarathy, Ruoming Jin
EDBT
2012
ACM
247views Database» more  EDBT 2012»
12 years 1 months ago
Heuristics-based query optimisation for SPARQL
Query optimization in RDF Stores is a challenging problem as SPARQL queries typically contain many more joins than equivalent relational plans, and hence lead to a large join orde...
Petros Tsialiamanis, Lefteris Sidirourgos, Irini F...