Talks and Poster Presentations (with Proceedings-Entry):

S. Bova, R. Ganian, St. Szeider:
"Quantified Conjunctive Queries on Partially Ordered Sets";
Talk: International Symposium on Parameterized and Exact Computation (IPEC), Wroclaw, Poland; 2014-09-10 - 2014-09-12; in: "IPEC 2014", LNCS / Springer, 8894 (2014), 122 - 134.

English abstract:
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 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.

Related Projects:
Project Head Stefan Szeider:
Exploiting New Types of Structure for Fixed Parameter Tractability

Project Head Stefan Szeider:
Parameterized Compilation

Project Head Stefan Szeider:
The Parameterized Complexity of Reasoning Problems

Created from the Publication Database of the Vienna University of Technology.