Asian-European Journal of Mathematics, 2024 (ESCI)
LetIn be the symmetric inverse semigroup on the finite chain Xn = {1,...,n} and let In,r = {α In:|im(α)|≤ r} for 1 ≤ r ≤ n - 1. A quasi-idempotent element is an element α In with the property that α α2 = α4. In this paper, we obtain a useful method by listing the subsets of Xn to build a (minimal) quasi-idempotent generating set of In,r both as a semigroup and also as an inverse semigroup for n ≥ 2 and 1 ≤ r ≤ n - 1.