2011/12/01 by Ros, Luca Motto · 1 citation
#03C75 #03E02 #03E10 #03E15 #03E55 #FOS: Mathematics #Logic (math.LO)
paper · doi:10.48550/arxiv.1112.0354
We show that if κ is a weakly compact cardinal then the embeddability relation on (generalized) trees of size κ is invariantly universal. This means that for every analytic quasi-order R on the generalized Cantor space 2κ there is an Lκ+ κ-sentence ϕ such that the embeddability relation on its models of size κ, which are all trees, is Borel bireducible (and, in fact, classwise Borel isomorphic) to R. In particular, this implies that the relation of embeddability on trees of size κ is complete for analytic quasi-orders. These facts generalize analogous results for κ=ω obtained in [LR05, FMR11], and it also partially extends a result from [Bau76] concerning the structure of the embeddability relation on linear orders of size κ.