The symbolic pfaffian method I: A generalization of the Gallucio-Loebl-Tesler Theorem
Abstract
The pfaffian number of a graph G, denoted by pf(G), is the minimum integer k such that the generating function of perfect matchings of G can be written as a linear combination of k pfaffians of signed adjacency matrices. The Galluccio-Loebl-Tesler Theorem states that pf(G) ≤ 4g, where g is the orientable genus of G. We generalize this theorem by relating the pfaffian number of a graph to another graph parameter: the symbolic pfaffian number, denoted by spf(G). Namely, we prove that pf(G) ≤ 2spf(G). Our proof is based on linear algebra arguments and does not depend on topological properties of graphs. As a consequence of our generalization, we conclude that pf(K2n) = 2𝒪(n log n), an improvement on the previous upper bound of 4𝒪(n2) based on the genus. We also consider lower bounds for pf(G) related to spf(G). In particular, we show that the graphs with pf(G) = 4 are the graphs with spf(G) = 2. On the other hand, we show that our main result is strictly more general than a previous generalization by Norine.
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BibTeX
@misc{junchaya2026symbolic,
title = {{The symbolic pfaffian method I: A generalization of the Gallucio-Loebl-Tesler Theorem}},
author = {Enrique Junchaya and Cláudio L. Lucchesi and Alberto A. A. Miranda},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.00468},
eprint = {2611.00468},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.00468},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - The symbolic pfaffian method I: A generalization of the Gallucio-Loebl-Tesler Theorem
AU - Enrique Junchaya
AU - Cláudio L. Lucchesi
AU - Alberto A. A. Miranda
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.00468
UR - https://arxiv.org/abs/2611.00468
AB - The pfaffian number of a graph G, denoted by pf(G), is the minimum integer k such that the generating function of perfect matchings of G can be written as a linear combination of k pfaffians of signed adjacency matrices. The Galluccio-Loebl-Tesler Theorem states that pf(G) ≤ 4^g, where g is the orientable genus of G. We generalize this theorem by relating the pfaffian number of a graph to another graph parameter: the symbolic pfaffian number, denoted by spf(G). Namely, we prove that pf(G) ≤ 2^spf(G). Our proof is based on linear algebra arguments and does not depend on topological properties of graphs. As a consequence of our generalization, we conclude that pf(K_2n) = 2^𝒪(n log n), an improvement on the previous upper bound of 4^𝒪(n^2) based on the genus. We also consider lower bounds for pf(G) related to spf(G). In particular, we show that the graphs with pf(G) = 4 are the graphs with spf(G) = 2. On the other hand, we show that our main result is strictly more general than a previous generalization by Norine.
ER -