On constructing small subgraphs in the budget-constrained random graph process

Fuente: arXiv
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Autores principales: Antoniuk, Sylwia, Díaz, Alberto Espuny, Petrova, Kalina, Stojaković, Miloš
Formato: Preprint
Publicado: 2026
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author Antoniuk, Sylwia
Díaz, Alberto Espuny
Petrova, Kalina
Stojaković, Miloš
author_facet Antoniuk, Sylwia
Díaz, Alberto Espuny
Petrova, Kalina
Stojaković, Miloš
contents Consider the budget-constrained random graph process introduced by Frieze, Krivelevich and Michaeli, where each time an edge is offered through the (standard) random graph process we must irrevocably decide whether to "purchase" this edge or not, with our goal being to construct a graph which satisfies some property within a given time $t$ and while purchasing at most $b$ edges. We consider the problem of constructing graphs containing certain fixed small subgraphs. We provide an optimal strategy for building a graph which contains a copy of $K_4$, showing that budget $b=ω(\max\{n^8/t^5,n^2/t\})$ suffices and that if $b=o(\max\{n^8/t^5,n^2/t\})$ then no strategy can a.a.s. produce a graph containing a copy of $K_4$. This resolves a problem raised by Iľkovič, León and Shu. More generally, we obtain analogously tight results for containing a wheel of any fixed size, or a graph consisting of a tree plus one additional universal vertex. We also tackle the problem of constructing graphs containing a copy of $K_5$, obtaining both lower and upper bounds on the optimal budget, though a gap remains in this case.
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id arxiv_https___arxiv_org_abs_2602_18325
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On constructing small subgraphs in the budget-constrained random graph process
Antoniuk, Sylwia
Díaz, Alberto Espuny
Petrova, Kalina
Stojaković, Miloš
Combinatorics
Consider the budget-constrained random graph process introduced by Frieze, Krivelevich and Michaeli, where each time an edge is offered through the (standard) random graph process we must irrevocably decide whether to "purchase" this edge or not, with our goal being to construct a graph which satisfies some property within a given time $t$ and while purchasing at most $b$ edges. We consider the problem of constructing graphs containing certain fixed small subgraphs. We provide an optimal strategy for building a graph which contains a copy of $K_4$, showing that budget $b=ω(\max\{n^8/t^5,n^2/t\})$ suffices and that if $b=o(\max\{n^8/t^5,n^2/t\})$ then no strategy can a.a.s. produce a graph containing a copy of $K_4$. This resolves a problem raised by Iľkovič, León and Shu. More generally, we obtain analogously tight results for containing a wheel of any fixed size, or a graph consisting of a tree plus one additional universal vertex. We also tackle the problem of constructing graphs containing a copy of $K_5$, obtaining both lower and upper bounds on the optimal budget, though a gap remains in this case.
title On constructing small subgraphs in the budget-constrained random graph process
topic Combinatorics
url https://arxiv.org/abs/2602.18325