  In this work, we consider a restricted case of the well studied Sorting by
Block Interchanges problem. We put an upper bound k on the length of the blocks
(substrings) to be interchanged at each step. We call the problem Sorting by
k-Block Interchanges. We show the problem to be NP-Hard for k=1. The problem is
easy for k=n-1, where n is the length of the permutation (the unbounded case).
Sorting by Block Interchanges is a very important and widely studied problem
with applications in comparative genomics.
