English

Schofield sequences in the Euclidean case

Representation Theory 2020-10-13 v2

Abstract

Let kk be a field and consider the path algebra kQkQ of the quiver QQ. A pair of indecomposable kQkQ-modules (Y,X)(Y,X) is called an orthogonal exceptional pair if the modules are exceptional and Hom(X,Y)=Hom(Y,X)=Ext1(X,Y)=0\operatorname{Hom}(X,Y)=\operatorname{Hom}(Y,X)=\operatorname{Ext}^{1}(X,Y)=0. Denote by F(X,Y)\mathcal{F}(X,Y) the full subcategory of objects having filtration with factors XX and YY. By the theorem of Schofield if ZZ is exceptional but not simple, then ZF(X,Y)Z\in\mathcal{F}(X,Y) for some orthogonal exceptional pair (Y,X)(Y,X), and ZZ is not a simple object in F(X,Y)\mathcal{F}(X,Y). In fact, there are precisely s(Z)1s(Z)-1 such pairs, where s(Z)s(Z) is the support of ZZ (i.e the number of nonzero components in dimZ{\underline\dim}Z). Whereas it is easy to construct ZZ given XX and YY, there is no convenient procedure yet to determine the possible modules XX (called Schofield submodules of ZZ) and then YY (called Schofield factors of ZZ), when ZZ is given. We present such an explicit procedure in the tame case, i.e when QQ is Euclidean.

Keywords

Cite

@article{arxiv.1912.07731,
  title  = {Schofield sequences in the Euclidean case},
  author = {Csaba Szántó and István Szöllősi},
  journal= {arXiv preprint arXiv:1912.07731},
  year   = {2020}
}

Comments

10 pages article, 100 pages appendix

R2 v1 2026-06-23T12:47:51.105Z