Commutative Bass rings, which form a special class of Gorenstein rings, have
been thoroughly investigated by Bass [1]. The definitions do
not carry over to non-commutative rings. However, in case one deals with
orders in separable algebras over fields, Bass orders can be defined. Drozd,
Kiricenko, and Roïter [3] and Roïter [6] have
clarified the structure of Bass orders, and they have classified them. These
Bass orders play a key role in the question of the finiteness of the
non-isomorphic indecomposable lattices over orders (cf. [2;
8]). We shall use the results of Drozd, Kiricenko, and Roïter
[3] to compute the Grothendieck groups of Bass orders
locally. Locally, the Grothendieck group of a Bass order (with the exception
of one class of Bass orders) is the epimorphic image of the direct sum of
the Grothendieck groups of the maximal orders containing it.