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The random \(k\)-matching-free process. (English) Zbl 1405.05164

Summary: Let \(\mathcal P\) be a graph property which is preserved by removal of edges, and consider the random graph process that starts with the empty \(n\)-vertex graph and then adds edges one-by-one, each chosen uniformly at random subject to the constraint that \(\mathcal P\) is not violated. These types of random processes have been the subject of extensive research over the last 20 years, having striking applications in extremal combinatorics, and leading to the discovery of important probabilistic tools. In this paper we consider the \(k\)-matching-free process where \(\mathcal P\) is the property of not containing a matching of size \(k\). We are able to analyze the behavior of this process for a wide range of values of \(k\); in particular we prove that if \(k=o(n)\) or if \(n-2k=o\bigg(\sqrt{n}/\log n\bigg)\) then this process is likely to terminate in a \(k\)-matching-free graph with the maximum possible number of edges, as characterized by P. Erdős and T. Gallai [Acta Math. Acad. Sci. Hung. 10, 337–356 (1959; Zbl 0090.39401)]. We also show that these bounds on \(k\) are essentially best possible, and we make a first step towards understanding the behavior of the process in the intermediate regime.

MSC:

05C80 Random graphs (graph-theoretic aspects)
05C70 Edge subsets with special properties (factorization, matching, partitioning, covering and packing, etc.)

Citations:

Zbl 0090.39401
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