PreprintarXiv licencearXiv
On the existence of F-irregular graphs for disconnected graphs F
Abstract
For a given graph F, a graph G is F-irregular if all its vertices have pairwise distinct F-degrees, where the F-degree of a vertex v is the number of subgraphs of G containing v and isomorphic to F. While the existence of F-irregular graphs has been actively studied for connected graphs F, the case where F is disconnected remains entirely unexplored. In this paper, we provide a complete solution to this problem. We prove that for every disconnected graph F with |E(F)| ≥ 2, there exist infinitely many F-irregular graphs. Conversely, if |E(F)| ≤ 1, we show that no non-trivial F-irregular graph exists.
Related
BibTeX
@misc{dovzhenok2026existence,
title = {{On the existence of $F$-irregular graphs for disconnected graphs $F$}},
author = {Tatiana Dovzhenok},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.18349},
eprint = {2610.18349},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.18349},
}
RIS
TY - UNPB
TI - On the existence of F-irregular graphs for disconnected graphs F
AU - Tatiana Dovzhenok
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.18349
UR - https://arxiv.org/abs/2610.18349
AB - For a given graph F, a graph G is F-irregular if all its vertices have pairwise distinct F-degrees, where the F-degree of a vertex v is the number of subgraphs of G containing v and isomorphic to F. While the existence of F-irregular graphs has been actively studied for connected graphs F, the case where F is disconnected remains entirely unexplored. In this paper, we provide a complete solution to this problem. We prove that for every disconnected graph F with |E(F)| ≥ 2, there exist infinitely many F-irregular graphs. Conversely, if |E(F)| ≤ 1, we show that no non-trivial F-irregular graph exists.
ER -