When is the evaluation of conjunctive queries tractable ? - Inria - Institut national de recherche en sciences et technologies du numérique Access content directly
Conference Papers Year : 2001

When is the evaluation of conjunctive queries tractable ?

Abstract

The evaluation of conjunctive queries is hard both with respect to its combined complexity (NP-complete) and its pa-rameterized complexity (W[1]-complete). It becomes trac-table (PTIME for combined complexity, FPT for parame-terized complexity), when the underlying graphs of the con-junctive queries have bounded tree-width [2]. We show that, in some sense, this is optimal both with respect to combined and parameterized complexity: For every class C of graphs, the evaluation of all conjunctive queries whose underlying graph is in C is tractable if, and only if, C has bounded tree-width. A technical result of independent interest is that the colored grid homomorphism problem is NP-complete and, if param-eterized by the grid size, W[1]-complete.
Fichier principal
Vignette du fichier
CQ-PTIME.pdf (277.73 Ko) Télécharger le fichier
Origin : Files produced by the author(s)
Loading...

Dates and versions

hal-01984895 , version 1 (17-01-2019)

Identifiers

  • HAL Id : hal-01984895 , version 1

Cite

Martin Grohe, Thomas Schwentick, Luc Segoufin. When is the evaluation of conjunctive queries tractable ?. STOC 2001 - Thirty-Third Annual ACM Symposium on Theory of Computing, Jul 2001, Heraklion, Greece. ⟨hal-01984895⟩

Collections

CNRS INRIA INRIA2
38 View
137 Download

Share

Gmail Facebook X LinkedIn More