The existence of directed BIBDs

All Directed BIBDs with k = 3 Exist

A directed BIBD with parameters (v,b,r,k,λ*) is a BIBD with parameters (v, b, r, k, 2λ*) in which each ordered pair of varieties occurs together in exactly λ* blocks. It is shown that λ*v(v 1) = 0 (mod 3) is a necessary and sufficient condition for the existence of a directed (v, b, r, k, λ*) BIBD with k = 3. Disciplines Physical Sciences and Mathematics Publication Details Seberry, J and Skill...

Existence of doubly near resolvable (v, 4, 3) BIBDs

The existence of doubly near resolvable (v, 2, 1)-BIBDs was established by Mullin and Wallis in 1975. For doubly near resolvable (v, 3, 2)-BIBDs, the existence problem was investigated by Lamken in 1994, and completed by Abel, Lamken and Wang in 2007. In this paper, we look at doubly near resolvable (v, 4, 3)-BIBDs; we establish that these exist whenever v ≡ 1 (mod 4) except for v = 9 and possi...

On the Existence of (v, 5, 1)-BIBDs

The Existence of DNR ( mt + 1 , m , m − 1 ) - BIBDs

A (v, m, m − 1)-BIBD D is said to be near resolvable (NRBIBD) if the blocks of D can be partitioned into classes R1, R2, . . . , Rv such that for each point x of D, there is precisely one class having no block containing x and each class contains precisely v − 1 points of the design. If an (v, m, λ)-NRBIBD has a pair of orthogonal resolutions, it is said to be doubly resolvable and is denoted D...

New combinatorial designs and their applications to authentication codes and secret sharing schemes

This paper introduces three new types of combinatorial designs, which we call external difference families (EDF), external BIBDs (EBIBD) and splitting BIBDs. An EDF is a special type of EBIBD, so existence of an EDF implies existence of an EBIBD. We construct optimal splitting A-codes by using EDF. Then we give a new bound on the number of shares required in robust secret sharing schemes (i.e.,...

On symmetric designs and binary 3-frameproof codes

In this paper, we study when the incidence matrix of a symmetric (v, k, λ)-BIBD is a 3-frameproof code. We show the existence of infinite families of symmetric BIBDs that are 3-frameproof codes, as well as infinite families of symmetric BIBDs that are not 3-frameproof codes.