Talk:T-design

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I'd be grateful if anyone could explain why 'partial incomplete block design' is the terminology could add that.

Charles Matthews 19:48, 19 Nov 2004 (UTC)

[edit] confusion

As usual with stuff concerning graph theory/combinatorics, conventions differ. in my syllabus it saids every 2-design is a block and vice versa

But more importantly , it says : Sλ(t,k,v) is a t-design , when :

  • the number of points is v
  • the number of points on a line is k
  • through every subset of the point set with t elements there are \lambda blocks

now the r defined here , is the number of blocks through one point x now some basic counting teaches me immediately :

{v-1 \choose t-1} \lambda= r {k-1 \choose t-1}


My syllabus apparently backs me up on this formula. My question, why should this be included in the definition when it is abundant as it (apparently) can be calculated immediately from the rest

My apologies if I am wrong, I am just a student and most of maths is still new to me, but I am very busy with it all.

Kind regards, Evilbu 16:58, 15 February 2006 (UTC)

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