Homomorphism Counts to Trees

Fuente: arXiv
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1. Verfasser: Dawar, Anuj
Format: Preprint
Veröffentlicht: 2024
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_version_ 1866912715639881728
author Dawar, Anuj
author_facet Dawar, Anuj
contents We construct a pair of non-isomorphic, bipartite graphs which are not distinguished by counting the number of homomorphisms to any tree. This answers a question motivated by Atserias et al. (LICS 2021). In order to establish the construction, we analyse the equivalence relations induced by counting homomorphisms to trees of diameter two and three and obtain necessary and sufficient conditions for two graphs to be equivalent. We show that three is the optimal diameter for our construction.
format Preprint
id arxiv_https___arxiv_org_abs_2405_19147
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Homomorphism Counts to Trees
Dawar, Anuj
Discrete Mathematics
Combinatorics
05C60 (primary) 68R10 (secondary)
G.2.1; G.2.2
We construct a pair of non-isomorphic, bipartite graphs which are not distinguished by counting the number of homomorphisms to any tree. This answers a question motivated by Atserias et al. (LICS 2021). In order to establish the construction, we analyse the equivalence relations induced by counting homomorphisms to trees of diameter two and three and obtain necessary and sufficient conditions for two graphs to be equivalent. We show that three is the optimal diameter for our construction.
title Homomorphism Counts to Trees
topic Discrete Mathematics
Combinatorics
05C60 (primary) 68R10 (secondary)
G.2.1; G.2.2
url https://arxiv.org/abs/2405.19147