Sorting by prefix block-interchanges

We initiate the study of sorting permutations using prefix block-interchanges, which exchange any a permutation with another non-intersecting interval. The goal is to transform given into identity as few such operations possible. give 2-approximation algorithm for this problem, well 4/3-approximation simple permutations; we prove tight lower and upper bounds on corresponding distance; bound largest value that distance can reach.