English

On asymorphisms of groups

Group Theory 2016-03-01 v1

Abstract

Let GG, HH be groups and κ\kappa be a cardinal. A bijection f:GHf:G\to H is caled on asymorphism if, for any X[G]<κX\in[G]^{<\kappa}, Y[H]<κY\in[H]^{<\kappa}, there exist X[G]<κX'\in[G]^{<\kappa}, Y[H]<κY'\in[H]^{<\kappa} such that for all xGx\in G and yHy\in H, we have f(Xx)Yf(x)f(Xx)\subseteq Y'f(x), f1(Yy)Xf1(y)f^{-1}(Yy)\subseteq X'f^{-1}(y). For a set SS, [S]<κ[S]^{<\kappa} denotes the set {SS:S<κ}\{S'\subseteq S: |S'|<\kappa\}. Let κ\kappa and γ\gamma be cardinals such that 0<κγ\aleph_0<\kappa\le\gamma. We prove that any two Abelian groups of cardinality γ\gamma are κ\kappa-asymorphic, but the free group of rank γ\gamma is not κ\kappa-asymorphic to an Abelian group provided that either κ<γ\kappa<\gamma or κ=γ\kappa=\gamma and κ\kappa is a singular cardinal. It is known [7] that if γ=κ\gamma = \kappa and κ\kappa is regular then any two groups of cardinality κ\kappa are κ\kappa-asymorphic.

Keywords

Cite

@article{arxiv.1602.08577,
  title  = {On asymorphisms of groups},
  author = {Igor Protasov and Serhii Slobodianiuk},
  journal= {arXiv preprint arXiv:1602.08577},
  year   = {2016}
}
R2 v1 2026-06-22T12:59:06.778Z