English

Permutational wreath pullbacks and framed braid-type groups

Group Theory 2026-04-08 v1 Geometric Topology

Abstract

Let σ ⁣:GSn\sigma\colon G \to S_n be a surjective homomorphism and let HH be a group. We introduce the \emph{permutational wreath pullback} HσG=HnσG, H \wr_\sigma G = H^n \rtimes_\sigma G, where the action of GG on HnH^n is induced by permutation of coordinates via σ\sigma, and undertake a systematic structural study of this construction. We determine the center and the abelianization in full generality. We further show that HσGH \wr_\sigma G admits a natural interpretation as the pullback of the classical wreath product HSnH \wr S_n along σ\sigma, providing a conceptual explanation for its functorial behavior. When HH is finitely generated abelian, we establish a criterion for the abelian kernel HnH^n to be characteristic and for HσGH \wr_\sigma G to inherit the RR_\infty-property from GG; we verify this criterion for kernels arising from the virtual braid group VBnVB_n and the virtual twin group VTnVT_n, obtaining new families of framed groups with the RR_\infty-property. Rigidity results show that the abelian kernel, nn, HH, and GG are determined by the abstract group HσGH \wr_\sigma G. Applications include uniform descriptions of classical, surface, virtual, and singular framed braid groups, and a reduction of splitting problems for framed surface braid groups to the classical Fadell--Neuwirth setting.

Keywords

Cite

@article{arxiv.2604.05281,
  title  = {Permutational wreath pullbacks and framed braid-type groups},
  author = {Ênio Leite and Oscar Ocampo},
  journal= {arXiv preprint arXiv:2604.05281},
  year   = {2026}
}

Comments

25 pages, Comments are welcome

R2 v1 2026-07-01T11:56:22.867Z