On the existence of an ultra central approximate identity for certain semigroup algebras

الأصل · EN

In this paper we characterize the existance of an ultra central approximate identity for ℓ¹(S), where S is a uniformly locally finite inverse semigroup. As an application, for the Brandt semigroup S=M⁰(G,I) over a non-empty set I, we show that ℓ¹(S) has an ultra central approximate identity if and only if I is finite.