Codes Correcting Transpositions of Consecutive Symbols

The problem of correcting transpositions (or swaps) of consecutive symbols in $ q $-ary strings is studied. A family of codes correcting a transposition at an arbitrary location is described and proved to have asymptotically optimal redundancy. Additionally, an improved construction is given over a binary alphabet. Bounds on the cardinality of codes correcting $ t = \textrm{const} $ transpositions are obtained. A lower bound on the achievable asymptotic rate of optimal codes correcting $ t = \tau n $ transpositions is derived. Finally, a construction of codes correcting all possible patterns of transpositions is presented, and the corresponding lower bound on the zero-error capacity of the $ q $-ary transposition channel is stated.