Generalized Steiner Systems
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چکیده
Generalized Steiner systems GSd t; k; v; g were ®rst introduced by Etzion and used to construct optimal constant-weight codes over an alphabet of size g 1 with minimum Hamming distance d, in which each codeword has length v and weight k. Much work has been done for the existence of generalized Steiner triple systems GS 2; 3; v; g. However, for block size four there is not much known on GSd 2; 4; v; g. In this paper, the necessary conditions for the existence of a GSd t; k; v; g are given, which answers an open problem of Etzion. Some singular indirect product constructions for GSd 2; k; v; g are also presented. By using both recursive and direct constructions, it is proved that the necessary conditions for the existence of a GS4 2; 4; v; g are also suf®cient for g 2; 3; 6: # 2001 John Wiley & Sons, Inc. J Combin Designs 9: 401±423, 2001
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تاریخ انتشار 2001