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Optimal Tight Equi‐Difference Conflict‐Avoiding Codes of Length n = 2k ± 1 and Weight 3
Authors:Shung‐Liang Wu  Hung‐Lin Fu
Institution:1. Department of Computer Science and Information Engineering, National United University, , Miaoli, 36003 Taiwan;2. Department of Applied Mathematics, National Chaio Tung University, , Hsin Chu, 30010 Taiwan
Abstract:For a k‐subset X of urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0001, the set of differences on X is the set urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0002 (mod n): urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0003 . A conflict‐avoiding code CAC of length n and weight k is a collection urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0004 of k‐subsets of urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0005 such that urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0006 = ? for any distinct urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0007. Let CAC(urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0008) be the class of all the CACs of length n and weight k. The maximum size of codes in CAC(n, k) is denoted by urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0009. A code urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0010 CAC(n, k) is said to be optimal if urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0011 = urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0012. An optimal code urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0013 is tight equi‐difference if urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0014 = urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0015 and each codeword in urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0016 is of the form urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0017. In this paper, the necessary and sufficient conditions for the existence problem of optimal tight equi‐difference conflict‐avoiding codes of length n = urn:x-wiley:10638539:media:jcd21332:jcd21332-math-0018 and weight 3 are given. © 2012 Wiley Periodicals, Inc. J. Combin. Designs 21: 223–231, 2013
Keywords:conflict‐avoiding codes  equi‐difference  optimal codes
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