Before revision:  In this paper we consider the problem of sorting unsigned permutations by prefix reversals and prefix transpositions , where a prefix reversal or a prefix transposition is applied always at the unsorted suffix of the given permutation. For this problem we first present a 3-approximation algorithm, which performs close to 2 in practice.
After revision:  In this paper we consider the problem of sorting unsigned permutations by prefix reversals and prefix transpositions , where a prefix reversal or a prefix transposition is applied always at the unsorted suffix of the permutation.