English

Representation-tame algebras need not be homologically tame

Representation Theory 2019-12-20 v1 Rings and Algebras

Abstract

We show that, also within the class of representation-tame finite dimensional algebras Λ\Lambda, the big left finitistic dimension of Λ\Lambda may be strictly larger than the little. In fact, the discrepancies FindimΛfindimΛFindim \Lambda - findim \Lambda need not even be bounded for special biserial algebras which constitute one of the (otherwise) most thoroughly understood classes of tame algebras. More precisely: For every positive integer rr, we construct a special biserial algebra Λ\Lambda with the property that findimΛ=r+1findim \Lambda = r + 1, while FindimΛ=2r+1Findim \Lambda = 2r + 1. In particular, there are infinite dimensional representations of Λ\Lambda which have finite projective dimension, while not being direct limits of {\it finitely generated\/} representations of finite projective dimension.

Keywords

Cite

@article{arxiv.1509.07945,
  title  = {Representation-tame algebras need not be homologically tame},
  author = {Birge Huisgen-Zimmermann},
  journal= {arXiv preprint arXiv:1509.07945},
  year   = {2019}
}