Partitioning subgraphs of profinite ordered graphs (Q2322548)

From MaRDI portal
scientific article
Language Label Description Also known as
English
Partitioning subgraphs of profinite ordered graphs
scientific article

    Statements

    Partitioning subgraphs of profinite ordered graphs (English)
    0 references
    0 references
    0 references
    0 references
    4 September 2019
    0 references
    Let \(\mathcal{K}\) be the class of all inverse limits \(G=\lim_{\leftarrow \, n\in \mathbb{N}}G_{n}\), where each \(G_n\) is a finite ordered graph. \(G\in \mathcal{K}\) is said to be universal if every \(B\in \mathcal{K}\) embeds continously into \(G\). In this paper, it is shown that for every finite ordered graph \(A\) there exists a least natural number \(k(A)\geq 1\) such that for every universal \(G\in \mathcal{K}\), for every finite Baire measurable partition of the set \(\binom{G}{A}\) of all copies of \(A\) in \(G\), there is a closed copy \(G^\prime\subseteq G\) of \(G\) such that \(\binom{G^\prime}{A}\) meets at most \(k(A)\) parts. Moreover, the probability that \(k(A)=1\), for a finite ordered graph \(A\), chosen randomly with uniform probability from all graphs on \(\{ 0,\ldots ,n-1\}\), tends to 1 as \(n\) grows to infinity and the class \(\mathcal{K}\) with Baire partitions satisfies with high probability the following partition property for a finite ordered graph \(A\): for every inverse limit of finite ordered graphs \(B\) there exists an inverse limit of finite ordered graph \(C\) such that for every Baire measurable partition of \(\binom{C}{A}\) to finitely many parts there is a closed copy of \(B\) in \(C\) such that \(\binom{B}{A}\) meets exactly one of the parts.
    0 references
    finite ordered graph
    0 references
    universal inverse limit
    0 references
    isomorphism type
    0 references
    Baire-measurable partition
    0 references
    0 references

    Identifiers

    0 references
    0 references
    0 references
    0 references
    0 references
    0 references
    0 references
    0 references