Good tilting modules and recollements of derived module categories
Abstract
Let be an infinitely generated tilting module of projective dimension at most one over an arbitrary associative ring , and let be the endomorphism ring of . In this paper, we prove that if is good then there exists a ring , a homological ring epimorphism and a recollement among the (unbounded) derived module categories of , of , and of . In particular, the kernel of the total left derived functor is triangle equivalent to the derived module category . Conversely, if the functor admits a fully faithful left adjoint functor, then is a good tilting module. We apply our result to tilting modules arising from ring epimorphisms, and can then describe the rings as coproducts of two relevant rings. Further, in case of commutative rings, we can weaken the condition of being tilting modules, strengthen the rings as tensor products of two commutative rings, and get similar recollements. Consequently, we can produce examples (from commutative algebra and -adic number theory, or Kronecker algebra) to show that two different stratifications of the derived module category of a ring by derived module categories of rings may have completely different derived composition factors (even up to ordering and up to derived equivalence),or different lengths. This shows that the Jordan-H\"older theorem fails even for stratifications by derived module categories, and also answers negatively an open problem by Angeleri-H\"ugel, K\"onig and Liu.
Cite
@article{arxiv.1012.2176,
title = {Good tilting modules and recollements of derived module categories},
author = {Hongxing Chen and Changchang Xi},
journal= {arXiv preprint arXiv:1012.2176},
year = {2014}
}