A. del Ŕıo‡

For a ring A with local units we investigate unital overrings T of A, and compare the automorphism groups Aut(A) and Aut(T). 1 Introduction, notation and preliminaries We recall (see e.g. [4]) that a ring A is said to have local units provided for every finite subset F of A, there is an idempotent e ∈ A such that F ⊂ eAe. In particular, any unital ring has local units. In many ways, rings with local units behave very similarly to rings with identity (see, for example, [3], [4], [5], [6], and [9].) Therefore, it is natural to wonder if the essence of rings with local unit