Golden Ratio Growth and Phase Transitions in Chromatic Counts of Circular Chord Graphs

Fuente: arXiv
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Auteurs principaux: Lopez-Bonilla, Rogelio N., Allagan, Julian, Langley, Shawn M., Clinton, Angel J.
Format: Preprint
Publié: 2025
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author Lopez-Bonilla, Rogelio N.
Allagan, Julian
Langley, Shawn M.
Clinton, Angel J.
author_facet Lopez-Bonilla, Rogelio N.
Allagan, Julian
Langley, Shawn M.
Clinton, Angel J.
contents We study generalized circular chord graphs $\mathcal C^{(k)}_n$, formed from a cycle $C_n$ by adding fixed-offset chords of length $k$ and, for even $n$, diameters. Using transfer matrix methods, we derive exact formulas for 3-colorings when $k=3$: for odd $n$, we obtain \[ P(\mathcal{C}_n^{(3)},3) = L_n + 2\cos\left(\frac{2πn}{3}\right) + 2s_n + 2 \] where $L_n$ is the Lucas sequence and $(s_n)$ satisfies $s_{n+3} = -s_{n+2} - s_n$, yielding golden-ratio asymptotic growth $φ^n + O(ρ^n)$ along odd indices. For even $n$, we construct a paired-window transfer matrix that exactly enumerates $P(\mathcal{C}_{2m}^{(3)},3)$ while capturing diameter constraints. The chromatic counts exhibit pronounced modular patterns across residue classes without universal vanishing rules (see OEIS A383733). We provide efficient algorithms for exact enumeration and demonstrate applications to cyclic scheduling problems where these results serve as feasibility engines for airline gate assignment, wireless sensor networks, and multiprocessor task coordination.
format Preprint
id arxiv_https___arxiv_org_abs_2509_05845
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Golden Ratio Growth and Phase Transitions in Chromatic Counts of Circular Chord Graphs
Lopez-Bonilla, Rogelio N.
Allagan, Julian
Langley, Shawn M.
Clinton, Angel J.
Combinatorics
Discrete Mathematics
68R10, 05C85
G.2.1; G.2.2; G.2.3; I.1.2
We study generalized circular chord graphs $\mathcal C^{(k)}_n$, formed from a cycle $C_n$ by adding fixed-offset chords of length $k$ and, for even $n$, diameters. Using transfer matrix methods, we derive exact formulas for 3-colorings when $k=3$: for odd $n$, we obtain \[ P(\mathcal{C}_n^{(3)},3) = L_n + 2\cos\left(\frac{2πn}{3}\right) + 2s_n + 2 \] where $L_n$ is the Lucas sequence and $(s_n)$ satisfies $s_{n+3} = -s_{n+2} - s_n$, yielding golden-ratio asymptotic growth $φ^n + O(ρ^n)$ along odd indices. For even $n$, we construct a paired-window transfer matrix that exactly enumerates $P(\mathcal{C}_{2m}^{(3)},3)$ while capturing diameter constraints. The chromatic counts exhibit pronounced modular patterns across residue classes without universal vanishing rules (see OEIS A383733). We provide efficient algorithms for exact enumeration and demonstrate applications to cyclic scheduling problems where these results serve as feasibility engines for airline gate assignment, wireless sensor networks, and multiprocessor task coordination.
title Golden Ratio Growth and Phase Transitions in Chromatic Counts of Circular Chord Graphs
topic Combinatorics
Discrete Mathematics
68R10, 05C85
G.2.1; G.2.2; G.2.3; I.1.2
url https://arxiv.org/abs/2509.05845