科研之友
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摘要
A group divisible design GD(k, lambda, t; tn) is alpha-resolvable if its blocks can be partitioned into classes such that each point of the design occurs in precisely alpha blocks in each class. The necessary conditions for the existence of such a design are n >= k, lambda t(n-1) = r(k-1), bk = rtn, k vertical bar alpha tn and alpha vertical bar r. It is shown in this paper that these conditions are also sufficient when k = 4 and t = 6 and 9, except for some possible exceptions.
