On Distinguishing Graphs and Cost Number using Automorphism Representations

Fuente: arXiv
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Autori principali: Gopaulsingh, Alexa, Molnár, Zalán, Banerjee, Amitayu
Natura: Preprint
Pubblicazione: 2025
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author Gopaulsingh, Alexa
Molnár, Zalán
Banerjee, Amitayu
author_facet Gopaulsingh, Alexa
Molnár, Zalán
Banerjee, Amitayu
contents A distinguishing coloring of a graph is a vertex coloring such that only the identity automorphism of the graph preserves the coloring. A 2-distinguishable graph is a graph which can be distinguished using 2 colors. The cost $ρ(G)$ of a 2-distinguishable graph is the smallest size of a color set of a distinguishing coloring of $G$. The determining number of a graph, $Det(G)$, is the minimum number of nodes, which if fixed by a coloring, would ensure that the coloring distinguishes the entire graph. Boutin (J. Combin. Math. Combin. Comput. 85: 161-171, 2013) posed an open problem which asks if $ρ(G)$ and $Det(G)$ can be arbitrarily far apart. It is trivial that it cannot be so for the case $Det(G) = 1$ but the answer was unknown for $Det(G) \geq 2$. We solve this problem for the case $Det(G) = 2$. We show that for the case $Det(G) = 2$, that not only is the cost bounded but in fact it takes small values with $ρ(G) = 2, \ 3$ or $4$. In order to establish this, the concept of the automorphism representation of a graph is developed. Graphs having equivalent automorphism representations implies that they have the same distinguishing number (note that just having isomorphic automorphism groups is not enough for this to hold). This prompts a factoring of graphs by which two graphs are distinguishably equivalent iff they have equivalent automorphism representations.
format Preprint
id arxiv_https___arxiv_org_abs_2505_21299
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On Distinguishing Graphs and Cost Number using Automorphism Representations
Gopaulsingh, Alexa
Molnár, Zalán
Banerjee, Amitayu
Combinatorics
Group Theory
05C15, 05C25
A distinguishing coloring of a graph is a vertex coloring such that only the identity automorphism of the graph preserves the coloring. A 2-distinguishable graph is a graph which can be distinguished using 2 colors. The cost $ρ(G)$ of a 2-distinguishable graph is the smallest size of a color set of a distinguishing coloring of $G$. The determining number of a graph, $Det(G)$, is the minimum number of nodes, which if fixed by a coloring, would ensure that the coloring distinguishes the entire graph. Boutin (J. Combin. Math. Combin. Comput. 85: 161-171, 2013) posed an open problem which asks if $ρ(G)$ and $Det(G)$ can be arbitrarily far apart. It is trivial that it cannot be so for the case $Det(G) = 1$ but the answer was unknown for $Det(G) \geq 2$. We solve this problem for the case $Det(G) = 2$. We show that for the case $Det(G) = 2$, that not only is the cost bounded but in fact it takes small values with $ρ(G) = 2, \ 3$ or $4$. In order to establish this, the concept of the automorphism representation of a graph is developed. Graphs having equivalent automorphism representations implies that they have the same distinguishing number (note that just having isomorphic automorphism groups is not enough for this to hold). This prompts a factoring of graphs by which two graphs are distinguishably equivalent iff they have equivalent automorphism representations.
title On Distinguishing Graphs and Cost Number using Automorphism Representations
topic Combinatorics
Group Theory
05C15, 05C25
url https://arxiv.org/abs/2505.21299