2023/08/24 by Héctor Jardón-Sánchez, Jardón-Sánchez, Héctor · 1 citation
Computer Science · Mathematics · #05C10 #05C83 (Secondary) #37A20 (Primary) 03E15 #Advanced Topology and Set Theory #Computability, Logic, AI Algorithms #Dynamical Systems (math.DS) #FOS: Mathematics #Logic (math.LO)
paper · pdf · doi:10.48550/arxiv.2308.13087
openalex publication_date 2023/08/24 · openalex created_date 2023/08/29 · openalex updated_date 2026/07/28
A framework to handle tree decompositions of the components of a Borel graph in a Borel fashion is introduced, along the lines of Tserunyan's Stallings Theorem for equivalence relations arXiv:1805.09506. This setting leads to a notion of accessibility for Borel graphs, together with a treeability criterion. This criterion is applied to show that, in particular, Borel equivalence relations associated to Borel graphs with accessible planar connected components are measure treeable, generalising results of Conley, Gaboriau, Marks, and Tucker-Drob arXiv:2104.07431 and Timar arXiv:1910.01307. It is also proven that uniformly locally finite Borel graphs with components of finite tree-width yield Borel treeable equivalence relations. Our results imply that p.m.p countable Borel equivalence relations with measured property (T) do not admit locally finite graphings with planar components a.s.