Quantified Conjunctive Queries on Partially Ordered Sets

Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 8894)


We study the computational problem of checking whether a quantified conjunctive query (a first-order sentence built using only conjunction as Boolean connective) is true in a finite poset (a reflexive, antisymmetric, and transitive directed graph). We prove that the problem is already \(\mathrm {NP}\)-hard on a certain fixed poset, and investigate structural properties of posets yielding fixed-parameter tractability when the problem is parameterized by the query. Our main algorithmic result is that model checking quantified conjunctive queries on posets of bounded width is fixed-parameter tractable (the width of a poset is the maximum size of a subset of pairwise incomparable elements). We complement our algorithmic result by complexity results with respect to classes of finite posets in a hierarchy of natural poset invariants, establishing its tightness in this sense.


Quantified conjunctive queries Posets Parameterized complexity 


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Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  1. 1.Vienna University of TechnologyViennaAustria

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