All Graphs with at most 8 nodes are 2-interval-PCGs

Fuente: arXiv
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Hauptverfasser: Calamoneri, Tiziana, Monti, Angelo, Petroni, Fabrizio
Format: Preprint
Veröffentlicht: 2022
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author Calamoneri, Tiziana
Monti, Angelo
Petroni, Fabrizio
author_facet Calamoneri, Tiziana
Monti, Angelo
Petroni, Fabrizio
contents A graph G is a multi-interval PCG if there exist an edge weighted tree T with non-negative real values and disjoint intervals of the non-negative real half-line such that each node of G is uniquely associated to a leaf of T and there is an edge between two nodes in G if and only if the weighted distance between their corresponding leaves in T lies within any such intervals. If the number of intervals is k, then we call the graph a k-interval-PCG; in symbols, G = k-interval-PCG (T, I1, . . . , Ik). It is known that 2-interval-PCGs do not contain all graphs and the smallest known graph outside this class has 135 nodes. Here we prove that all graphs with at most 8 nodes are 2-interval-PCGs, so doing one step towards the determination of the smallest value of n such that there exists an n node graph that is not a 2-interval-PCG.
format Preprint
id arxiv_https___arxiv_org_abs_2202_13844
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle All Graphs with at most 8 nodes are 2-interval-PCGs
Calamoneri, Tiziana
Monti, Angelo
Petroni, Fabrizio
Discrete Mathematics
Combinatorics
A graph G is a multi-interval PCG if there exist an edge weighted tree T with non-negative real values and disjoint intervals of the non-negative real half-line such that each node of G is uniquely associated to a leaf of T and there is an edge between two nodes in G if and only if the weighted distance between their corresponding leaves in T lies within any such intervals. If the number of intervals is k, then we call the graph a k-interval-PCG; in symbols, G = k-interval-PCG (T, I1, . . . , Ik). It is known that 2-interval-PCGs do not contain all graphs and the smallest known graph outside this class has 135 nodes. Here we prove that all graphs with at most 8 nodes are 2-interval-PCGs, so doing one step towards the determination of the smallest value of n such that there exists an n node graph that is not a 2-interval-PCG.
title All Graphs with at most 8 nodes are 2-interval-PCGs
topic Discrete Mathematics
Combinatorics
url https://arxiv.org/abs/2202.13844