Even-freeness of cyclic 2-designs [article]

Yuichiro Fujiwara
2012 arXiv   pre-print
A Steiner 2-design of block size k is an ordered pair (V, B) of finite sets such that B is a family of k-subsets of V in which each pair of elements of V appears exactly once. A Steiner 2-design is said to be r-even-free if for every positive integer i =< r it contains no set of i elements of B in which each element of V appears exactly even times. We study the even-freeness of a Steiner 2-design when the cyclic group acts regularly on V. We prove the existence of infinitely many nontrivial
more » ... ner 2-designs of large block size which have the cyclic automorphisms and higher even-freeness than the trivial lower bound but are not the points and lines of projective geometry.
arXiv:1210.7516v1 fatcat:otp3xpspdfb3dg3cf6ilso53fq