… The present paper is devoted to some isomorphisms of homological groups and formulas
of homological dimensions of special modules over a formal triangular matrix ring T = …
always means a formal triangular matrix ring in this paper, where A and B are rings and U is
a (B,A)-bimodule. By [10, Theorem 1.5], the category T-Mod of left T-modules is equivalent
to the category Ω whose objects are triples M = (M1 …