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Size Bounds for Conjunctive Queries with General Functional Dependencies
, 2009
"... This paper resolves the main open question left by Gottlob, Lee, and Valiant (PODS 2009) [8], establishing tight worstcase bounds for the size of the result Q(D) of a conjunctive query Q to a database D given an arbitrary set of functional dependencies. We show that the lower bound presented in [8] ..."
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Cited by 2 (0 self)
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This paper resolves the main open question left by Gottlob, Lee, and Valiant (PODS 2009) [8], establishing tight worstcase bounds for the size of the result Q(D) of a conjunctive query Q to a database D given an arbitrary set of functional dependencies. We show that the lower bound presented in [8
Constraint Satisfaction, Bounded Treewidth, and FiniteVariable Logics
, 2002
"... We systematically investigate the connections between constraint satisfaction problems, structures of bounded treewidth, and definability in logics with a finite number of variables. We first show that constraint satisfaction problems on inputs of treewidth less than k are definable using Datalog ..."
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Cited by 72 (12 self)
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We systematically investigate the connections between constraint satisfaction problems, structures of bounded treewidth, and definability in logics with a finite number of variables. We first show that constraint satisfaction problems on inputs of treewidth less than k are definable using
When is the evaluation of conjunctive queries tractable
 In Proceedings of the 33rd ACM Symposium on Theory of Computing
, 2001
"... zINRIARocquencourt Abstract The evaluation of conjunctive queries is hard both with respect to its combined complexity (NPcomplete) and its parameterized complexity (W[1]complete). It becomes tractable (PTIME for combined complexity, FPT for parameterized complexity), when the underlying graphs o ..."
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Cited by 42 (4 self)
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of the conjunctive queries have bounded treewidth [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 treewidth
Efficient Approximations of Conjunctive Queries
"... When finding exact answers to a query over a large database is infeasible, it is natural to approximate the query by a more efficient one that comes from a class with good bounds on the complexity of query evaluation. In this paper we study such approximations for conjunctive queries. These queries ..."
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Cited by 5 (3 self)
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closure properties of classes of conjunctive queries to the existence of approximations. We also show that in many cases, the size of approximations is bounded by the size of the query they approximate. We establish a number of results showing how combinatorial properties of queries affect properties
AnswerSet Programming with Bounded Treewidth
, 2009
"... In this paper, we present a novel approach to the evaluation of propositional answerset programs. In particular, for programs with bounded treewidth, our algorithm is capable of (i) computing the number of answer sets in linear time and (ii) enumerating all answer sets with linear delay. Our algori ..."
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Cited by 9 (7 self)
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In this paper, we present a novel approach to the evaluation of propositional answerset programs. In particular, for programs with bounded treewidth, our algorithm is capable of (i) computing the number of answer sets in linear time and (ii) enumerating all answer sets with linear delay. Our
Definability and Descriptive Complexity on Databases of Bounded TreeWidth
 Database TheoryICDT'99, volume 1540 of Lecture Notes in Computer Science
, 1999
"... . We study the expressive power of various query languages on relational databases of bounded treewidth. Our first theorem says that fixedpoint logic with counting captures polynomial time on classes of databases of bounded treewidth. This result should be seen on the background of an importa ..."
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Cited by 34 (10 self)
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. We study the expressive power of various query languages on relational databases of bounded treewidth. Our first theorem says that fixedpoint logic with counting captures polynomial time on classes of databases of bounded treewidth. This result should be seen on the background
Combinatorial Optimization on Graphs of Bounded Treewidth
, 2007
"... There are many graph problems that can be solved in linear or polynomial time with a dynamic programming algorithm when the input graph has bounded treewidth. For combinatorial optimization problems, this is a useful approach for obtaining fixedparameter tractable algorithms. Starting from trees an ..."
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Cited by 51 (4 self)
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There are many graph problems that can be solved in linear or polynomial time with a dynamic programming algorithm when the input graph has bounded treewidth. For combinatorial optimization problems, this is a useful approach for obtaining fixedparameter tractable algorithms. Starting from trees
The parameterized complexity of conjunctive query . . .
, 2005
"... This thesis is an expository treatment of the article “When is the evaluation of conjunctive queries tractable? ” by Grohe, Schwentick and Segoufin [13]. The topic of the article is the tractability of conjunctive queries to structures. In particular, the authors use a graphtheoretic approach to th ..."
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This thesis is an expository treatment of the article “When is the evaluation of conjunctive queries tractable? ” by Grohe, Schwentick and Segoufin [13]. The topic of the article is the tractability of conjunctive queries to structures. In particular, the authors use a graphtheoretic approach
On Digraph Coloring Problems and Treewidth Duality
 20th IEEE Symposium on Logic in Computer Science (LICS
, 2005
"... It is known that every constraintsatisfaction problem (CSP) reduces, and is in fact polynomially equivalent, to a digraph coloring problem. By carefully analyzing the constructions, we observe that the reduction is quantifierfree. Using this, we illustrate the power of the logical approach to CSPs ..."
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Cited by 53 (2 self)
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tractable CSPs. The novelty is that our bounds are a tight function of the treewidth of the underlying instance. As a corollary we get a new proof that there exist tractable CSPs without bounded treewidth duality. ∗ This work was partially supported by CICYT TIN200404343 and by the European Commision
Polynomials of Bounded TreeWidth
, 2001
"... We introduce a new sparsity conditions, the treewidth, on multivariate polynomials in n variables (over some ring R) and show that under this condition many otherwise intractable computational problems involving these polynomials become solvable in polynomial (in some cases even linear) time in ..."
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Cited by 3 (1 self)
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We introduce a new sparsity conditions, the treewidth, on multivariate polynomials in n variables (over some ring R) and show that under this condition many otherwise intractable computational problems involving these polynomials become solvable in polynomial (in some cases even linear) time
Results 11  20
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2,137