Group Divisible Designs with Two Associate Classes and with Two Unequal Groups
نویسندگان
چکیده
A group divisible design GDD(m,n; 3, λ1, λ2) is an ordered triple (V,G,B), where V is a m+ n-set of symbols, G is a partition of V into 2 sets of sizes m,n, each set being called group, and B is a collection of 3-subsets (called blocks) of V , such that each pair of symbols from the same group occurs in exactly λ1 blocks; and each pair of symbols from different groups occurs in exactly λ2 blocks. In this paper, we find necessary and sufficient conditions for the existence of a GDD(m,n; 3, λ1, λ2) with λ1 ≥ λ2. AMS Subject Classification: 05B05, 05B07
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