Summary: Asymptotically Good Codes Correcting Insertions, Deletions, and
Leonard J. Schulman \Lambda David Zuckerman y
We present simple, polynomialtime encodable and decodable codes which are asymptotically good for channels
allowing insertions, deletions and transpositions. As a corollary, they achieve exponential error probability
in a stochastic model of insertiondeletion.
Keywords: error correcting codes, insertion, deletion, transposition, edit distance, asymptotically good,
\Lambda College of Computing, Georgia Institute of Technology, Atlanta GA 303320280. Email: email@example.com.
y On leave from the University of Texas at Austin. Email: firstname.lastname@example.org. Supported in part by NSF NYI Grant No.
CCR9457799, a David and Lucile Packard Fellowship for Science and Engineering, and an Alfred P. Sloan Research Fellowship.
In an asynchronous noisy channel, characters of the received message are not definitively identified with
antecedents in the transmitted message. We describe a code which allows for correction of data modified in
the following ways:
A. Insertion and deletion of characters. (Note that this implies also alteration of characters.)
B. Transpositions of blocks of data: a message of the form ABC is transformed into ACB. (Note that this