engleski

Quasi-symmetric designs

A t-(v, k, λ) design is a finite incidence structure consisting of a set V of v points and a collection B of k-subsets of V, called blocks, with the property that any t-subset of V is contained in exactly λ blocks. A t-design is quasi-symmetric if any two blocks intersect either in x or in y points, for non-negative integers x < y. The classi cation of quasi- symmetric designs for t = 2 is a difficult open problem and there are many triples (v, k, λ) for which existence is unknown. Quasi-symmetric designs have important connections with strongly regular graphs and self-orthogonal codes. We use computational methods for the construction of designs with pre- scribed automorphism groups, such as the Kramer-Mesner method and a method based on clique search.

quasi-symmetric designs

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