English

Realisability problem in arrow categories

Algebraic Topology 2019-10-09 v3 Combinatorics Representation Theory

Abstract

In this paper we raise the realisability problem in arrow categories. Namely, for a fixed category C\mathcal{C} and for arbitrary groups HG1×G2H\le G_1\times G_2, is there an object ϕ ⁣:A1A2\phi \colon A_1 \rightarrow A_2 in Arr(C)\operatorname{Arr}(\mathcal{C}) such that AutArr(C)(ϕ)=H\operatorname{Aut}_{\operatorname{Arr}(\mathcal{C})}(\phi) = H, AutC(A1)=G1\operatorname{Aut}_{\mathcal{C}}(A_1) = G_1 and AutC(A2)=G2\operatorname{Aut}_{\mathcal{C}}(A_2) = G_2? We are interested in solving this problem when C=HoTop\mathcal C =\mathcal{H}oTop_*, the homotopy category of pointed topological spaces. To that purpose, we first settle that question in the positive when C=Graphs\mathcal C = \mathcal{G}raphs. Then, we construct an almost fully faithful functor from Graphs\mathcal{G}raphs to CDGA\operatorname{CDGA}, the category of commutative differential graded algebras, that provides among other things, a positive answer to our question when C=CDGA\mathcal C = \operatorname{CDGA} and, as long as we work with finite groups, when C=HoTop\mathcal C =\mathcal{H}oTop_*. Some results on representability of concrete categories are also obtained.

Keywords

Cite

@article{arxiv.1901.03152,
  title  = {Realisability problem in arrow categories},
  author = {Cristina Costoya and David Méndez and Antonio Viruel},
  journal= {arXiv preprint arXiv:1901.03152},
  year   = {2019}
}

Comments

24 pages. Minor corrections. To appear in Collectanea Mathematica

R2 v1 2026-06-23T07:08:02.078Z