Approximate amenability of certain inverse semigroup algebras

In this article, the approximate amenability of semigroup algebra ℓ1(S) is investigated, where (S) is a uniformly locally finite inverse semigroup. Indeed, we show that for a uniformly locally finite inverse semigroup (S), the notions of amenability, approximate amenability and bounded approximate amenability of ℓ1(S) are equivalent. We use this to give a direct proof of the approximate amenability of ℓ1(S) for a Brandt semigroup (S). Moreover, we characterize the approximate amenability of ℓ1(S), where S is a uniformly locally finite band semigroup.