Article ID Journal Published Year Pages File Type
4649651 Discrete Mathematics 2009 8 Pages PDF
Abstract

Each parallel class of a uniformly resolvable design (URD) contains blocks of only one block size kk (denoted kk-pc). The number of kk-pcs is denoted rkrk. The necessary conditions for URDs with vv points, index one, blocks of size 3 and 5, and r3,r5>0r3,r5>0, are v≡15(mod30). If rk>1rk>1, then v≥k2v≥k2, and r3=(v−1−4⋅r5)/2r3=(v−1−4⋅r5)/2. For r5=1r5=1 these URDs are known as group divisible designs. We prove that these necessary conditions are sufficient for r5=3r5=3 except possibly v=105v=105, and for r5=2,4,5r5=2,4,5 with possible exceptions (v=105,165,285,345v=105,165,285,345) New labeled frames and labeled URDs, which give new URDs as ingredient designs for recursive constructions, are the key in the proofs.

Related Topics
Physical Sciences and Engineering Mathematics Discrete Mathematics and Combinatorics
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