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On the Enumeration Complexity of Unions of Conjunctive Queries
[article]
2021
arXiv
pre-print
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contain disequalities. ...
Nevertheless, we prove that for several classes of queries, free-connexity fully captures the tractable UCQs. ...
ACKNOWLEDGMENTS The authors are greatly thankful to Benny Kimelfeld for his advice. The work of Nofar Carmeli was supported by the Irwin and Joan Jacobs Fellowship and by the Google PhD Fellowship. ...
arXiv:1812.03831v5
fatcat:35apyblfrbgktocq7n5rbjpmeq
The HOM Problem is EXPTIME-Complete
2016
SIAM journal on computing (Print)
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Tree automata with disequality and implicit HOM equality constraints. ...
As a consequence, we obtain several EXPTIMEcompleteness results for problems on images of regular tree languages under tree homomorphisms, like set inclusion, regularity (HOM problem), and finiteness of ...
The homomorphism (HOM) problem questions, for a given regular tree language L described by a tree automaton and a tree homomorphism H, whether H(L) is regular. ...
doi:10.1137/140999104
fatcat:yniqldd2wnegjfrgyuwxbmefjy
Approximately Counting Answers to Conjunctive Queries with Disequalities and Negations
[article]
2022
arXiv
pre-print
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However, if there are neither disequalities nor negations, we prove the existence of an FPRAS for queries of bounded fractional hypertreewidth, strictly generalising the recently established FPRAS for ...
We establish an exhaustive classification into tractable and intractable cases if φ is a conjunctive query with disequalities and negations: ∙ If there is a constant bound on the arity of φ, and if the ...
Consequently by ( 2 ) there is a homomorphism h from A(ϕ) to B(ϕ, D) that extends τ and satisfies all disequalities in ∆(ϕ), that is, h(x i ) = h(x j ) for all {x i , x j } ∈ ∆(ϕ). ...
arXiv:2103.12468v2
fatcat:qlf52fkbnvcatnhasbvbhyhj3e
The HOM problem is decidable
2013
Journal of the ACM
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For example, the tree lan- Tree homomorphisms are a powerful representation system. ...
An automaton of this new class essentially recognizes the intersection of a tree automaton with disequality constraints and the image of a regular language through a tree homomorphism. ...
In [10] it is shown that for any given regular language a and any given This is in contrast with top-down tree transducers: tree homomorphisms are also a particular case of top-down tree transducer, ...
doi:10.1145/2508028.2501600
fatcat:pe7p526xjzg3dpzhbhdrv4zu3y
The HOM problem is decidable
2010
Proceedings of the 42nd ACM symposium on Theory of computing - STOC '10
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For example, the tree lan- Tree homomorphisms are a powerful representation system. ...
An automaton of this new class essentially recognizes the intersection of a tree automaton with disequality constraints and the image of a regular language through a tree homomorphism. ...
In [10] it is shown that for any given regular language a and any given This is in contrast with top-down tree transducers: tree homomorphisms are also a particular case of top-down tree transducer, ...
doi:10.1145/1806689.1806757
dblp:conf/stoc/GodoyGRA10
fatcat:rtuai6ewurahff6qu2y4w5zaou
Boolean Tensor Decomposition for Conjunctive Queries with Negation
2019
International Conference on Database Theory
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Its data complexity matches that of the InsideOut and PANDA algorithms for the positive subquery of the input query and is expressed in terms of the fractional hypertree width and the submodular width ...
We show how to rewrite queries with negation on bounded-degree relations into equivalent conjunctive queries with not-all-equal (NAE) predicates, which are a multi-dimensional analog of disequality ( = ...
The color-coding technique [8] underlies existing approaches to answering queries with disequalities [27, 9, 21] , the homomorphic embedding problem [14] , and motif finding and counting in computational ...
doi:10.4230/lipics.icdt.2019.21
dblp:conf/icdt/KhamisNOS19
fatcat:pntxmsf5crf3jgc3nz6qwlpktm
Automata on Infinite Trees with Equality and Disequality Constraints Between Siblings
2016
Proceedings of the 31st Annual ACM/IEEE Symposium on Logic in Computer Science - LICS '16
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Roughly speaking we consider parity tree automata where some transitions are guarded and can be used only when the two direct sub-trees of the current node are equal/disequal. ...
The first one is by Bogaert and Tison who considered a model of automata on finite ranked trees where one can check equality and disequality constraints between direct subtrees: they proved that this class ...
language T of finite trees and a tree homomorphism h, whether the image h(T ) of T under h is a regular tree language. ...
doi:10.1145/2933575.2934504
dblp:conf/lics/CarayolLS16
fatcat:2niy35qp4bgevi6yqp5zxymxhe
Data Structure Specifications via Local Equality Axioms
[chapter]
2005
Lecture Notes in Computer Science
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We describe a complete decision procedure for axioms without disequalities, and practical heuristics for the full language. ...
We describe a program verification methodology for specifying global shape properties of data structures by means of axioms involving predicates on scalar fields, pointer equalities, and pointer disequalities ...
Acknowledgments This research was supported in part by NSF Grants CCR-0326577, and CCF-0524784. ...
doi:10.1007/11513988_47
fatcat:omztu7cb7rhubk7b453pwxth3u
Enumeration Complexity of Conjunctive Queries with Functional Dependencies
[article]
2021
arXiv
pre-print
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Further conclusions of our development include a dichotomy for enumeration with linear delay, and a dichotomy for CQs with disequalities. ...
A known dichotomy classifies the acyclic self-join-free CQs into those that admit such enumeration, and those that do not. ...
(⊥, b, c) ∈ S I . ⊓ ⊔
Fig. 1 1 Join tree T of H(Q + ) for head-paths of length greater than 2. ...
arXiv:1712.07880v2
fatcat:glrorkdwwrdqfkqdsigt4a5ha4
Boolean Tensor Decomposition for Conjunctive Queries with Negation
[article]
2019
arXiv
pre-print
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Its data complexity matches that of the best known algorithms for the positive subquery of the input query and is expressed in terms of the fractional hypertree width and the submodular width. ...
We show how to rewrite queries with negation on bounded-degree relations into equivalent conjunctive queries with not-all-equal (NAE) predicates, which are a multi-dimensional analog of disequality (not-equal ...
The color-coding technique [9] underlies existing approaches to answering
queries with disequalities [11, 26, 37], the homomorphic embedding problem [18], and mo-
tif finding and counting in computational ...
arXiv:1712.07445v5
fatcat:j7zth5dztnfmllt4w3dss5mqom
The Tractability of CSP Classes Defined by Forbidden Patterns
2012
The Journal of Artificial Intelligence Research
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The constraint satisfaction problem (CSP) is a general problem central to computer science and artificial intelligence. ...
Recently, some authors have considered hybrid properties that restrict the constraint hypergraph and the relations simultaneously. ...
Acknowledgments The authors acknowledge support from ANR Project ANR-10-BLAN-0210, EPSRC grants EP/F011776/1 and EP/I011935/1, ERC Starting Grant PARAMTIGHT (No. 280152), and EPSRC platform grant EP/F028288 ...
doi:10.1613/jair.3651
fatcat:6tfaqcsoeffu7oxfwrkj426wz4
Majority constraints have bounded pathwidth duality
2008
European journal of combinatorics (Print)
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This implies that the constraint satisfaction problem for any fixed structure with a majority polymorphism is in NL. ...
We show that such a problem is equivalent to deciding whether the given structure admits a homomorphism from an obstruction belonging to a certain class of structures of bounded pathwidth. ...
Part of this work was done when both authors visited the Isaac Newton Institute for Mathematical Sciences, Cambridge. The financial support provided by the Institute is gratefully acknowledged. ...
doi:10.1016/j.ejc.2007.11.020
fatcat:5obi63teijbqhmdhw5kzvepvn4
Tractable Lineages on Treelike Instances
2016
Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems - PODS '16
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2016 pre-print arXiv:1604.02761v1 fatcat:6jqe2yq75zcdzjcsxtxcozpwza
By contrast, we can strengthen the previous dichotomy to lineages, and show that there are even UCQs with disequalities that have superpolynomial OBDDs on all unbounded-treewidth graph classes; we give ...
This dichotomy relies on recent polynomial bounds on the extraction of planar graphs as minors, and implies lower bounds in non-probabilistic settings, for query evaluation and match counting in subinstance-closed ...
We also thank the anonymous reviewers of PODS 2016 for their valuable comments, in particular for strengthening Theorem 9.7 to tree-depth. ...
doi:10.1145/2902251.2902301
dblp:conf/pods/AmarilliBS16
fatcat:skanmavk2vfrfgop3wqq3ebpoe
Tractable Reasoning in a Fragment of Separation Logic
[chapter]
2011
Lecture Notes in Computer Science
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In 2004, Berdine, Calcagno and O'Hearn introduced a fragment of separation logic that allows for reasoning about programs with pointers and linked lists. ...
Entailment between two such formulae then reduces to a graph homomorphism problem. We also discuss natural syntactic extensions that render entailment intractable. ...
We would like to thank Nikos Gorogiannis for interesting and helpful discussions and the anonymous referees for helpful suggestions on how to improve the presentation of the paper. ...
doi:10.1007/978-3-642-23217-6_16
fatcat:wrjr6muoofebjjjbwkfbtjoccu
Tree pattern query minimization
2002
The VLDB journal
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(based on homomorphism techniques), and reduction. ...
Tree patterns form a natural basis to query treestructured data such as XML and LDAP. ...
Acknowledgements We would like to thank Dan Suciu and the reviewers of this paper for their insightful comments and suggestions, which helped improve this paper substantially. ...
doi:10.1007/s00778-002-0076-7
fatcat:5cxp6mi27bewhi4milnij3zdfu
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