Lexicographic code
Lexicographic codes or lexicodes are greedily generated error-correcting codes with remarkably good properties. They were produced independently by Levenshtein[1] and Conway and Sloane [2] and are known to be linear over some finite fields.
Construction
A lexicode of minimum distance d and length n over a finite field is generated by starting with the all-zero vector and iteratively adding the next vector (in lexicographic order) of minimum Hamming distance d from the vectors added so far. As an example, the length-3 lexicode of minimum distance 2 would consist of the vectors marked by an "X" in the following example:
Vector In code? 000 X 001 010 011 X 100 101 X 110 X 111
Since lexicodes are linear, they can also be constructed by means of their basis. [3]
Notes
- ↑ V.I. Levenstein. A class of systematic codes. Soviet Math. Dokl, 1(1):368-371, 1960.
- ↑ J.H. Conway and N.J.A Sloane. Lexicographic codes: error-correcting codes from game theory. IEEE Transactions on Information Theory, 32:337-348, 1986.
- ↑ Ari Trachtenberg, Designing Lexicographic Codes with a Given Trellis Complexity, IEEE Transactions on Information Theory, January 2002.
External links
- Bob Jenkins table of binary lexicodes
- On-line generator for lexicodes and their variants
- "Sloane's A075928 : List of codewords in binary lexicode with Hamming distance 4 written as decimal numbers.", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- Error-Correcting Codes on Graphs: Lexicodes, Trellises and Factor Graphs
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