,
Juha Kontinen
,
Fabian Müller
,
Heribert Vollmer
,
Fan Yang
Creative Commons Attribution 3.0 Unported license
We study descriptive complexity of counting complexity classes in the range from #P to #*NP. A corollary of Fagin’s characterization of NP by existential second-order logic is that #P can be logically described as the class of functions counting satisfying assignments to free relation variables in first-order formulae. In this paper we extend this study to classes beyond #P and extensions of first-order logic with team semantics. These team-based logics are closely related to existential second-order logic and its fragments, hence our results also shed light on the complexity of counting for extensions of first-order logic in Tarski’s semantics. Our results show that the class #*NP can be logically characterized by independence logic and existential second-order logic, whereas dependence logic and inclusion logic give rise to subclasses of #*NP and #P, respectively. We also study the function class generated by inclusion logic and relate it to the complexity class TotP, which is a subclass of #P. Our main technical result shows that the problem of counting satisfying assignments for monotone Boolean Sigma_1-formulae is #*NP-complete with respect to Turing reductions as well as complete for the function class generated by dependence logic with respect to first-order reductions.
@InProceedings{haak_et_al:LIPIcs.MFCS.2019.19,
author = {Haak, Anselm and Kontinen, Juha and M\"{u}ller, Fabian and Vollmer, Heribert and Yang, Fan},
title = {{Counting of Teams in First-Order Team Logics}},
booktitle = {44th International Symposium on Mathematical Foundations of Computer Science (MFCS 2019)},
pages = {19:1--19:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-117-7},
ISSN = {1868-8969},
year = {2019},
volume = {138},
editor = {Rossmanith, Peter and Heggernes, Pinar and Katoen, Joost-Pieter},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2019.19},
URN = {urn:nbn:de:0030-drops-109634},
doi = {10.4230/LIPIcs.MFCS.2019.19},
annote = {Keywords: team-based logics, counting classes, finite model theory, descriptive complexity}
}