Non-Stabilizing Parallel Chip-Firing Games

Fuente: arXiv
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Hauptverfasser: Ji, David, Li, Michael, Wang, Daniel
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Veröffentlicht: 2024
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_version_ 1866929472407601152
author Ji, David
Li, Michael
Wang, Daniel
author_facet Ji, David
Li, Michael
Wang, Daniel
contents In 2010, Kominers and Kominers proved that any parallel chip-firing game on $G(V,\,E)$ with $|σ|\geq 4|E|-|V|$ chips stabilizes. Recently, Bu, Choi, and Xu made the bound exact: all games with $|σ|< |E|$ chips or $|σ|> 3|E|-|V|$ chips stabilize. Meanwhile, Levine found a "devil's staircase'' pattern in the plot of the activity of parallel chip-firing games against their density of chips. The stabilizing bound of Bu, Choi, and Xu corresponds to the top and bottom stairs of this staircase, in which the activity is 1 and 0, respectively. In this paper, we analyze the middle stair of the staircase, corresponding to activity $\frac{1}{2}$. We prove that all parallel chip-firing games with $2|E|-|V|< |σ|< 2|E|$ have period $T\neq 3,\,4$. In fact, this is exactly the range of $|σ|$ for which all games are non-stabilizing. We conjecture that all parallel chip-firing games with $2|E|-|V|< |σ|<2|E|$ have $T=2$ and thus activity $\frac{1}{2}$. This conjecture has been proven for trees by Bu, Choi, and Xu, cycles by Dall'asta, and complete graphs by Levine. We extend Levine's method of conjugate configurations to prove the conjecture on complete bipartite graphs $K_{a,a}$.
format Preprint
id arxiv_https___arxiv_org_abs_2408_10508
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Non-Stabilizing Parallel Chip-Firing Games
Ji, David
Li, Michael
Wang, Daniel
Combinatorics
05C57 68R10
In 2010, Kominers and Kominers proved that any parallel chip-firing game on $G(V,\,E)$ with $|σ|\geq 4|E|-|V|$ chips stabilizes. Recently, Bu, Choi, and Xu made the bound exact: all games with $|σ|< |E|$ chips or $|σ|> 3|E|-|V|$ chips stabilize. Meanwhile, Levine found a "devil's staircase'' pattern in the plot of the activity of parallel chip-firing games against their density of chips. The stabilizing bound of Bu, Choi, and Xu corresponds to the top and bottom stairs of this staircase, in which the activity is 1 and 0, respectively. In this paper, we analyze the middle stair of the staircase, corresponding to activity $\frac{1}{2}$. We prove that all parallel chip-firing games with $2|E|-|V|< |σ|< 2|E|$ have period $T\neq 3,\,4$. In fact, this is exactly the range of $|σ|$ for which all games are non-stabilizing. We conjecture that all parallel chip-firing games with $2|E|-|V|< |σ|<2|E|$ have $T=2$ and thus activity $\frac{1}{2}$. This conjecture has been proven for trees by Bu, Choi, and Xu, cycles by Dall'asta, and complete graphs by Levine. We extend Levine's method of conjugate configurations to prove the conjecture on complete bipartite graphs $K_{a,a}$.
title Non-Stabilizing Parallel Chip-Firing Games
topic Combinatorics
05C57 68R10
url https://arxiv.org/abs/2408.10508