no code implementations • 29 Dec 2020 • Georg Gottlob, Matthias Lanzinger, Davide Mario Longo, Cem Okulmus, Reinhard Pichler
Constraint Satisfaction Problems (CSPs) play a central role in many applications in Artificial Intelligence and Operations Research.
1 code implementation • 2 Sep 2020 • Wolfgang Fischl, Georg Gottlob, Davide Mario Longo, Reinhard Pichler
To cope with the intractability of answering Conjunctive Queries (CQs) and solving Constraint Satisfaction Problems (CSPs), several notions of hypergraph decompositions have been proposed -- giving rise to different notions of width, noticeably, plain, generalized, and fractional hypertree width (hw, ghw, and fhw).
1 code implementation • 20 Nov 2018 • Wolfgang Fischl, Georg Gottlob, Davide M. Longo, Reinhard Pichler
To cope with the intractability of answering Conjunctive Queries (CQs) and solving Constraint Satisfaction Problems (CSPs), several notions of hypergraph decompositions have been proposed -- giving rise to different notions of width, noticeably, plain, generalized, and fractional hypertree width (hw, ghw, and fhw).
Databases
no code implementations • 17 Mar 2018 • Leopoldo Bertossi, Georg Gottlob, Reinhard Pichler
This use of Datalog$^\pm$ is extended to give a set semantics to duplicates in Datalog$^\pm$ itself.
2 code implementations • 3 Nov 2016 • Wolfgang Fischl, Georg Gottlob, Reinhard Pichler
It is known that hw(H) <= k can be checked in polynomial time for fixed k, while checking ghw(H) <= k is NP-complete for any k greater than or equal to 3.
Databases Computational Complexity