Two possible concepts of rank in inverse semigroup theory, the intermediate
I-rank and the upper I-rank, are investigated for the finite aperiodic Bra
ndt semigroup. The so-called large I-rank is found for an arbitrary finite
Brandt semigroup, and the result is used, to obtain the large rank of the i
nverse semigroup of all proper subpermutations of a finite set.