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Merkey, Phillip Roy 2014-12-16T06:18:16Z 2014-12-16T06:18:16Z 10000-01-01 1986 1986 In chapter 1 we investigate the A(,s)(n,d) problem in the Plotkin Region. The problem is to finding the maximum number of codewords in a code on an alphabet with s symbols that has length n and minimum Hamming distance d. The Plotkin Region is the set of n and d such that sd > t(s - 1)n. We define Generalized Hadamard matrices, using a notion of orthogonality over a group, and show that these matrices give rise to certain A(,s)(n,d) codes. Two general constructions for A(,s)(n,d) codes, which apparently do not depend on Hadamard matrices, are given. Lastly we discuss a computer implemented algorithm to search for A(,3)(15,11). In chapter 2 we discuss the problem of finding the number of information symbols in a BCH code with design parameters n, b and d. This work generalizes the work of Berlekamp where he completely answers the problem for the case of the "simple" BCH codes (the case b = 0). In the general case (where b is arbitrary) we show the problem to be equivalent to counting certain walks in a directed graph. By considering the adjacency matrix for the graph we find a efficient method of computing I(n,d,b) and we find the asymptotic growth of I(n,d,b) as n, d and b increase while the ratios d/n and b/n are fixed. Made available in DSpace on 2014-12-16T06:18:16Z (GMT). No. of bitstreams: 1 8701565.pdf: 5094327 bytes, checksum: 62675a94d0e7d276ce4988d09a4465df (MD5) Previous issue date: 1986 Embargo set by: Seth Robbins for item 71411 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 147 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986. http://hdl.handle.net/2142/71245 (UMI)AAI8701565 Mathematics Topics in Coding Theory: 1. The A(,s)(n,d) Problem in The Plotkin Region. 2. Number of Information Symbols in a Bch Code text Mathematics Mathematics University of Illinois at Urbana-Champaign Dissertation Ph.D.