On the existence of balanced bipartite designs, II
نویسنده
چکیده
A block, considered as a set of elements together with its adjacency matrix M, is called a B-block if M is the adjacency matrix of a complete bipartite graph Kk,, k, . A balanced bipartite design with parameters b, u, r, k, h, kl, k2 (briefly BBD(u, k, A; kl)) is an arrangement of u elements into b B-blocks such that every B-block contains k = kl + ki elements, every element occurs in exactly r B-blocks and any two distinct elements are linked in exactly h B-blocks. Given fixed k and kl , there is always a minimal value of h such that the necessary conditions for the existence of a BBD are satisfied for some IJ. It was shown in [3] that, with exactly one exception, these necessary conditions are sufficient when k = 3,4 and 5. It is shown here that the necessary conditions are also sufficient when kl = 1, k > 2 and when k = 6, with two exceptions in the later case. Furthermore, several infinite families of BBD’s with kl = 2, k > 5 are constructed.
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ورودعنوان ژورنال:
- Discrete Mathematics
دوره 9 شماره
صفحات -
تاریخ انتشار 1974