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Bibliographic Details
Main Authors: Backman, Spencer, Loehr, Nicholas A., Warrington, Gregory S.
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.15451
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author Backman, Spencer
Loehr, Nicholas A.
Warrington, Gregory S.
author_facet Backman, Spencer
Loehr, Nicholas A.
Warrington, Gregory S.
contents This article introduces a quantized chip-firing model with close connections to the theory of rational lattice paths and rational parking functions. Given a graph with a sink and positive integers a,b,c with gcd(a,b)=1, a set S of vertices fires by the following rule. Each vertex in S provisionally sends c chips to the sink and a/b chips to each non-sink neighbor outside of S. The novel feature is that the total number of chips leaving from or arriving at any vertex gets rounded down to the nearest integer before being finalized. We define the notions of chip configurations being superstable, k-stable, or k-skeletal in this model. When c=1 and the graph is complete, superstable configurations correspond to rational parking functions. There is a bijection between superstable configurations and k-skeletal configurations for each k. We establish these results by building a combinatorial theory of k-skeletal rational lattice paths (both unlabeled and labeled) and translating that theory to chip configurations. There is a group structure on the set of chip configurations modulo firing and borrowing moves. We show that this group is isomorphic to the product of b-1 copies of the integers modulo a; and, for each k, each coset of chip configurations in this group contains a unique k-skeletal representative.
format Preprint
id arxiv_https___arxiv_org_abs_2603_15451
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quantized rational chip-firing
Backman, Spencer
Loehr, Nicholas A.
Warrington, Gregory S.
Combinatorics
05A15, 05A19, 05C57
This article introduces a quantized chip-firing model with close connections to the theory of rational lattice paths and rational parking functions. Given a graph with a sink and positive integers a,b,c with gcd(a,b)=1, a set S of vertices fires by the following rule. Each vertex in S provisionally sends c chips to the sink and a/b chips to each non-sink neighbor outside of S. The novel feature is that the total number of chips leaving from or arriving at any vertex gets rounded down to the nearest integer before being finalized. We define the notions of chip configurations being superstable, k-stable, or k-skeletal in this model. When c=1 and the graph is complete, superstable configurations correspond to rational parking functions. There is a bijection between superstable configurations and k-skeletal configurations for each k. We establish these results by building a combinatorial theory of k-skeletal rational lattice paths (both unlabeled and labeled) and translating that theory to chip configurations. There is a group structure on the set of chip configurations modulo firing and borrowing moves. We show that this group is isomorphic to the product of b-1 copies of the integers modulo a; and, for each k, each coset of chip configurations in this group contains a unique k-skeletal representative.
title Quantized rational chip-firing
topic Combinatorics
05A15, 05A19, 05C57
url https://arxiv.org/abs/2603.15451