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The complexity of acyclic conjunctive queries revisited [article]

Arnaud Durand
2006 arXiv   pre-print
A natural notion of query acyclicity for this language is introduced and we study the complexity of a large number of variants or generalizations of acyclic query problems in that context (Boolean or not  ...  In this paper, we consider first-order logic over unary functions and study the complexity of the evaluation problem for conjunctive queries described by such kind of formulas.  ...  In this paper, we revisit the complexity of acyclic conjunctive queries under a different angle.  ... 
arXiv:cs/0605008v1 fatcat:jkbyspg7rfeqhdjiydb5zkqkye

Repair checking in inconsistent databases

Foto N. Afrati, Phokion G. Kolaitis
2009 Proceedings of the 12th International Conference on Database Theory - ICDT '09  
Key property of weakly acyclic sets of tgds: The solution aware chase terminates in polynomial time.  ...  Theorem If Σ is the union of a weakly acyclic set of LAV tgds and a set of egds, then the subset-repair checking problem w.r.t. Σ is in PTIME; in fact, it is in LOGSPACE. Proof Idea.  ...  Σ Note Thus, in many cases, lower bounds for the complexity of the ⊕-repair checking problem yield lower bounds for the complexity of the consistent query answering problem.  ... 
doi:10.1145/1514894.1514899 dblp:conf/icdt/AfratiK09 fatcat:lvijjkbivnallpzuugigf2w634

Page 1961 of Mathematical Reviews Vol. , Issue 2001C [page]

2001 Mathematical Reviews  
We then generalize the notion of acyclicity and define a parameter called query width that captures the ‘degree of cyclicity’ of a query: in particular, a query is acyclic if and only if its query width  ...  acyclic queries.  ... 

A Negative Conjunctive Query is Easy if and only if it is Beta-Acyclic

Johann Brault-Baron, Marc Herbstritt
2012 Annual Conference for Computer Science Logic  
An important tractable class of conjunctive queries are the α-acyclic (or acyclic, for short) conjunctive queries.  ...  It is known that the data complexity of a Conjunctive Query (CQ) is determined only by the way its variables are shared between atoms, reflected by its hypergraph.  ...  Acknowledgments The author expresses his gratitude to Étienne Grandjean for careful, multiple readings of the successive versions of this paper, despite his busy schedule, until any doubtful or unclear  ... 
doi:10.4230/lipics.csl.2012.137 dblp:conf/csl/Brault-Baron12 fatcat:hjhsfirtdzfm5cxpz5cpaduxg4

Semantic Width Revisited (Extended Abstract)

Georg Gottlob, Matthias Lanzinger, Reinhard Pichler
2019 Alberto Mendelzon Workshop on Foundations of Data Management  
Acknowledgements This work was supported by the Austrian Science Fund (FWF):P30930-N35.  ...  Such semantic widths can be interpreted as measures of the inherent structural complexity of the underlying question posed by the query, whereas classical notions of width express the complexity of a specific  ...  Let Q be the class of all conjunctive queries and w : Q → R + be some property of the query. We define semantic w as sem-w(q) := inf{w(q ) | q q}, where denotes homomorphic equivalence.  ... 
dblp:conf/amw/GottlobLP19 fatcat:ogj3p4bu6rga7afex43rfe5msi

Conjunctive query containment revisited [chapter]

Chandra Chekuri, Anand Rajaraman
1997 Lecture Notes in Computer Science  
We consider the problems of conjunctive query containment and minimization, which are known to be NP-complete, and show that these problems can be solved in polynomial time for the class of acyclic queries  ...  We then consider the problem of ÿnding an equivalent query to a given conjunctive query Q that has the least number of subgoals.  ...  Acknowledgements The inspiration for considering the treewidth of the incidence graph came from the work of Khanna and Motwani [13] .  ... 
doi:10.1007/3-540-62222-5_36 fatcat:isjuvoxu45d5xiiovx7ydn4xi4

Conjunctive query containment revisited

Chandra Chekuri, Anand Rajaraman
2000 Theoretical Computer Science  
We consider the problems of conjunctive query containment and minimization, which are known to be NP-complete, and show that these problems can be solved in polynomial time for the class of acyclic queries  ...  We then consider the problem of ÿnding an equivalent query to a given conjunctive query Q that has the least number of subgoals.  ...  Acknowledgements The inspiration for considering the treewidth of the incidence graph came from the work of Khanna and Motwani [13] .  ... 
doi:10.1016/s0304-3975(99)00220-0 fatcat:obimws4n7zd23azmjuvhakseyu

Data Exchange: Query Answering for Incomplete Data Sources

Foto Afrati, Chen Li, Vassia Pavlaki
2008 Proceedings of the Third International ICST Conference on Scalable Information Systems  
We prove that computing certain answers (under both semantics) for unions of conjunctive queries can be done in polynomial time when the schema mapping contains constraints that consist of a weakly acyclic  ...  We use the chase to compute a universal instance which is materialized over the target schema and is used to compute the certain answers to unions of conjunctive queries.  ...  COMPLEXITY OF QUERY ANSWERING In this section we investigate the complexity of the query answering problem in IDE settings.  ... 
doi:10.4108/icst.infoscale2008.3476 dblp:conf/infoscale/AfratiLP08 fatcat:qjsyv3ueofde7dneihyqotjc64

Conjunctive Query Evaluation by Search Tree Revisited [chapter]

Albert Atserias
2004 Lecture Notes in Computer Science  
We investigate the question of evaluating conjunctive queries with a time-bound guarantee that is measured as a function of the size of the minimal search-tree.  ...  The most natural and perhaps most frequently used method for testing membership of an individual tuple into a conjunctive query is based on searching trees of partial solutions, or search-trees.  ...  I am also grateful to Moshe Vardi for providing useful pointers and for the discussion of ideas related to Theorem 2.  ... 
doi:10.1007/978-3-540-30570-5_4 fatcat:fuznd2tskvefxkxprztb2mtc3i

Containment of acyclic conjunctive queries with negated atoms or arithmetic comparisons

Evgeny Sherkhonov, Maarten Marx
2017 Information Processing Letters  
Acknowledgements We thank the anonymous referees for their valuable comments. This research was supported by NWO under project number 612.001.012 (DEX).  ...  Introduction We revisit the containment problem for conjunctive queries, one of the classical fundamental problems in database theory.  ...  Acyclic conjunctive queries have been studied as one of the restrictions [17, 8] . Conjunctive queries expanded with negated atoms or arithmetic comparisons are used in practice as well.  ... 
doi:10.1016/j.ipl.2016.12.005 fatcat:5gttsywndbevpi5lv6yut2xvpq

A Parameterized Complexity View on Description Logic Reasoning [article]

Ronald de Haan
2018 arXiv   pre-print
We substantiate our argument by means of three case studies. The first case study is about the problem of concept satisfiability for the logic ALC with respect to nearly acyclic TBoxes.  ...  The multi-dimensional framework of parameterized complexity theory is able to provide a much more detailed image of the complexity of reasoning problems.  ...  This work was supported by the Austrian Science Fund (FWF), project J4047.  ... 
arXiv:1808.03852v1 fatcat:hiswv5lrdjcbjfdf3isk7jxop4

The complexity of acyclic conjunctive queries

Georg Gottlob, Nicola Leone, Francesco Scarcello
2001 Journal of the ACM  
This paper deals with the evaluation of acyclic Boolean conjunctive queries in relational databases.  ...  We also show that the acyclic versions of the following well-known database and AI problems are all LOGCFL-complete: The Query Output Tuple problem for conjunctive queries, Conjunctive Query Containment  ...  Moreover, we are very indebted to the anonymous referees for suggesting a large number of improvements.  ... 
doi:10.1145/382780.382783 fatcat:junfs4dbfrcijjog2ns5kpp4ty

On the Complexity of Database Queries

Christos H. Papadimitriou, Mihalis Yannakakis
1999 Journal of computer and system sciences (Print)  
We revisit the issue of the complexity of database queries, in the light of the recent parametric refinement of complexity theory.  ...  We show that, if the query size (or the number of variables in the query) is considered as a parameter, then the relational calculus and its fragments (conjunctive queries, positive queries) are classified  ...  ACKNOWLEDGMENTS We appreciate the feedback from the PODS program committee and Moshe Vardi.  ... 
doi:10.1006/jcss.1999.1626 fatcat:zcnwenpklrc2pmenaabcoup7xe

Stable Model Semantics for Tuple-Generating Dependencies Revisited

Mario Alviano, Michael Morak, Andreas Pieris
2017 Proceedings of the 36th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems - PODS '17  
We then perform an in-depth complexity analysis of query answering under prominent classes of NTGDs based on the main decidability paradigms for TGDs, namely weak-acyclicity, guardedness and stickiness  ...  Interestingly, weakly-acyclic NTGDs give rise to robust and highly expressive query languages that allow us to solve in a declarative way problems in the second level of the polynomial hierarchy.  ...  Acknowledgements: We thank the anonymous referees for their helpful feedback.  ... 
doi:10.1145/3034786.3034794 dblp:conf/pods/AlvianoMP17 fatcat:jbbnvkoxijf6bpdku2wdkfaz6u

Lifted Successor Generation Using Query Optimization Techniques

Augusto B. Corrêa, Florian Pommerening, Malte Helmert, Guillem Francès
2020 Proceedings of the ... International Conference on Automated Planning and Scheduling  
Interestingly, a large number of the action schemas in the standard benchmarks result in acyclic conjunctive queries, for which query evaluation is tractable.  ...  While this simplifies the design of other parts of the planner, in several benchmarks the grounding process causes an exponential blowup that puts otherwise solvable tasks out of reach of the planners.  ...  We thank Bram Ridder for his assistance on the usage of the L-RPG planner and Mikhail Soutchanski for his assistance with the Organic Synthesis domain.  ... 
doi:10.1609/icaps.v30i1.6648 fatcat:ts5r2nuxzfcy7bgif43qr5snai
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