English

Copies of the Random Graph: the 2-localization

Logic 2017-09-26 v1

Abstract

Let GG be a countable graph containing a copy of the countable random graph (Erd\H{o}s-R\'enyi graph, Rado graph), Emb(G)Emb (G) the monoid of its self-embeddings, P(G)={f[G]:fEmb(G)}{\mathbb P} (G)=\{f[G]: f\in Emb (G)\} the set of copies of GG contained in GG, and IG{\mathcal I}_G the ideal of subsets of GG which do not contain a copy of GG. We show that the poset <P(G),>< {\mathbb P} (G), \subset>, the algebra P(G)/IGP (G)/{\mathcal I}_G, and the inverse of the right Green's pre-order <Emb(G),R>< Emb (G),\preceq ^R > have the 2-localization property. The Boolean completions of these pre-orders are isomorphic and satisfy the following law: for each double sequence [bnm:<n,m>ω×ω][b_{nm}: < n, m > \in \omega \times \omega ] of elements of B{\mathbb B} nω  mω  bnm=TBt(<ωω)  nω  φTn+1ω  kn  bkφ(k),\textstyle \bigwedge_{n \in \omega}\; \bigvee_{m \in \omega}\; b_{nm} = \bigvee_{{\mathcal T} \,\in \, Bt ({}^{<\omega}\omega)}\; \bigwedge_{n \in \omega}\; \bigvee_{\varphi \,\in \,{\mathcal T} \cap {}^{n+1}\omega}\; \bigwedge_{k\leq n}\; b_{k\varphi (k)}, where Bt(<ωω)Bt ({}^{<\omega}\omega) denotes the set of all binary subtrees of the tree <ωω{}^{<\omega}\omega.

Keywords

Cite

@article{arxiv.1411.3144,
  title  = {Copies of the Random Graph: the 2-localization},
  author = {Miloš S. Kurilić and Stevo Todorčević},
  journal= {arXiv preprint arXiv:1411.3144},
  year   = {2017}
}

Comments

17 pages

R2 v1 2026-06-22T06:56:04.361Z