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Quasi-Symmetric Designs with Good Blocks

✍ Scribed by T. P. McDonough; V. C. Mavron

Publisher
John Wiley and Sons
Year
1995
Tongue
English
Weight
460 KB
Volume
3
Category
Article
ISSN
1063-8539

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✦ Synopsis

The article is concerned with a characterization of quasi-symmetric (QS) designs with intersection numbers 0 and y. It uses the idea of a good block. Such a block G has the property that for any block B with IG n B J = y, every point is on a block containing G n B. It is proved that if a QS design II with intersection numbers 0 and y has a good block, then n must (i) be affine, symmetric, a linear space or (ii) have one of two possible exceptional parameter sets. Only one example is known in case (ii). If all blocks of H are good and I'I is not a linear space, then it is a projective or affine geometry or it is an extension (in a more general sense than usual) of a projective plane of order y2 or y 3 + y. 0 1995 John Wiley & Sons, he.

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