Derived Equivalent Mates of Triangular Matrix Algebras

A triangular matrix algebra over a field k is defined by a triplet (R, S, M) where R and S are k-algebras and RMS is an SR-bimodule. We show that if R, S and M are finite dimensional and the global dimensions of R and S are finite, then the triangular matrix algebra corresponding to (R, S, M) is derived equivalent to the one corresponding to (S, R, DM), where DM = Homk(M, k) is the dual of M , viewed as a R-S-bimodule. Therefore any triangular matrix algebra satisfying some finiteness conditions has a natural mate – another triangular matrix algebra derived equivalent to it.