✦ LIBER ✦

A characterization of the extensions of symmetric designs

✍ Scribed by A Baartmans; M.S Shrikhande

Publisher: Elsevier Science
Year: 1985
Tongue: English
Weight: 241 KB
Volume: 57
Category: Article
ISSN: 0012-365X
DOI: 10.1016/0012-365x(85)90182-7

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✦ Synopsis

Let D be a quasi-symmetric design with block intersection numbers 0 and y. For any fixed block B of D, let D B denote the incidence structure whose points are the points of D not in B and whose blocks are the blocks of D disjoint from B. If D is an extension of a symmetric design, Cameron showed that D, is a design and the parameters of D are exactly one of four types. We prove the converse: If D B is a design, then D is the extension of a symmetric design.

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