A decomposition structure of resonance graphs that are daisy cubes
Zhongyuan Che, Zhibo Chen
TL;DR
This work addresses the structural understanding of resonance graphs $R(G)$ for plane bipartite graphs, proving that $R(G)$ is a daisy cube precisely when $G$ is peripherally 2-colorable. It introduces a decomposition framework with respect to a finite face $s$ and a constructive proper labeling that yields an isometric embedding of $R(G)$ into an $n$-dimensional hypercube, with an algorithm to generate the labeling for all perfect matchings. The results extend to plane weakly elementary bipartite graphs whose nontrivial elementary components are peripherally 2-colorable and provide two distinct binary codings: one embedding $R(G)$ as a finite distributive lattice and another as a daisy cube, revealing differing structural insights. Collectively, these findings offer a practical, constructive approach to understanding resonance graphs, enabling isometric embeddings and enabling comparisons between daisy-cube and distributive-lattice representations of $R(G)$, with potential implications for related combinatorial chemistry models and graph-theoretic analyses.
Abstract
It has recently been shown in [\emph{Discrete Appl. Math.} {\bf 366} (2025) 75--85] that the resonance graph of a plane elementary bipartite graph $G$ is a daisy cube if and only if $G$ is peripherally 2-colorable. Let $G$ be a peripherally 2-colorable graph and $R(G)$ be its resonance graph. We provide a decomposition structure of $R(G)$ with respect to an arbitrary finite face of $G$ together with a proper labelling for the vertex set of $R(G)$. An algorithm is obtained to generate a proper labelling for all perfect matchings of $G$ which induces an isometric embedding of $R(G)$ as a daisy cube into an $n$-dimensional hypercube, where $n$ is the isometric dimension of $R(G)$. Moreover, the algorithm can be applied to generate such a proper labelling for all perfect matchings of any plane weakly elementary bipartite graph whose each elementary component with more than two vertices is peripherally 2-colorable. We also compare two binary codings for all perfect matchings of $G$ which induces distinct structures on $R(G)$: one as a daisy cube and the other as a finite distributive, respectively.
