Prefix transpositions on binary and ternary strings

The problem of Sorting by Prefix Transpositions asks for the minimum number of prefix transpositions required to sort the elements of a given permutation. In this paper, we study a variant of this problem where the prefix transpositions act not on permutations but on strings over an alphabet of fixed size. Here, we determine the minimum number of prefix transpositions required to sort the binary and ternary strings, with polynomial time algorithms for these sorting problems.