,
Ondřej Kuželka
,
Yuanhong Wang
,
Yuyi Wang
Creative Commons Attribution 4.0 International license
The Weighted First-Order Model Counting Problem (WFOMC) asks to compute the weighted sum of models of a given first-order logic sentence over a given domain. It can be solved in time polynomial in the domain size for sentences from the two-variable fragment with counting quantifiers, known as C^2. This polynomial-time complexity is known to be retained when extending C^2 by one of the following axioms: linear order axiom, tree axiom, forest axiom, directed acyclic graph axiom or connectedness axiom. An interesting question remains as to which other axioms can be added to the first-order sentences in this way. We provide a new perspective on this problem by associating WFOMC with graph polynomials. Using WFOMC, we define Weak Connectedness Polynomial and Strong Connectedness Polynomials for first-order logic sentences. It turns out that these polynomials have the following interesting properties. First, they can be computed in polynomial time in the domain size for sentences from C^2. Second, we can use them to solve WFOMC with all of the existing axioms known to be tractable as well as with new ones such as bipartiteness, strong connectedness, having k connected components, etc. Third, the well-known Tutte polynomial can be recovered as a special case of the Weak Connectedness Polynomial, and the Strict and Non-Strict Directed Chromatic Polynomials can be recovered from the Strong Connectedness Polynomials.
@InProceedings{kuang_et_al:LIPIcs.CSL.2026.7,
author = {Kuang, Qipeng and Ku\v{z}elka, Ond\v{r}ej and Wang, Yuanhong and Wang, Yuyi},
title = {{Bridging Weighted First Order Model Counting and Graph Polynomials}},
booktitle = {34th EACSL Annual Conference on Computer Science Logic (CSL 2026)},
pages = {7:1--7:23},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-411-6},
ISSN = {1868-8969},
year = {2026},
volume = {363},
editor = {Guerrini, Stefano and K\"{o}nig, Barbara},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2026.7},
URN = {urn:nbn:de:0030-drops-254316},
doi = {10.4230/LIPIcs.CSL.2026.7},
annote = {Keywords: Weighted First-Order Model Counting, Axiom, Enumerative Combinatorics, Tutte Polynomial}
}
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