منابع مشابه
New constructions of divisible designs
261 Davis, J.A., New constructions of divisible designs, Discrete Mathematics 120 (1993) 261-268. A construction is given for a (p2"(p+l),p,p2"+ 1(p+l),p2"+ ,p"(p+l)) (pa prime) divisible difference set in the group H x z~.+, where His any abelian group of order p+ 1. This can be used to generate a symmetric semi-regular divisible design; this is a new set of parameters for .l. 1 ;<'0, and thos...
متن کاملMatrix constructions of family (A) group divisible designs
In this note we use matrices to construct group divisible designs (GDDs). The constructions of GDDs of the form A 0 D + A ® D will be carried out in two cases. The first case uses the incidence matrix D of a GDD with a certain (0,1) matrix A. The second case uses the incidence matrix D of a BIBD with A as in the first case. In both cases necessary and sufficient conditions in terms of parameter...
متن کاملSome constructions of divisible designs from Laguerre geometries
In the nineties, A.G. Spera introduced a construction principle for divisible designs. Using this method, we get series of divisible designs from finite Laguerre geometries. We show a close connection between some of these divisible designs and divisible designs whose construction was based on a conic in a plane of a 3-dimensional projective space.
متن کاملNew Constructions of Lotto Designs
An LD(n, k, p, t; b) Lotto Design is a set of b k-sets (blocks) of an n-set such that any p-set intersects at least one k-set in t or more elements. Let L(n, k, p, t) denote the minimum number of blocks in any LD(n, k, p, t; b) Lotto Design. We shall discuss several techniques for constructing Lotto designs and determining upper bounds for L(n, k, p, t).
متن کاملNew Constructions for Covering Designs
A (v, k, t) covering design, or covering, is a family of k-subsets, called blocks, chosen from a v-set, such that each t-subset is contained in at least one of the blocks. The number of blocks is the covering’s size, and the minimum size of such a covering is denoted by C(v, k, t). This paper gives three new methods for constructing good coverings: a greedy algorithm similar to Conway and Sloan...
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 1993
ISSN: 0012-365X
DOI: 10.1016/0012-365x(93)90586-i