A polynomial ideal associated to any $t$-$(v,k,\lambda)$ design
Abstract
We consider ordered pairs where is a finite set of size and is some collection of -element subsets of such that every -element subset of is contained in exactly "blocks" for some fixed . We represent each block by a zero-one vector of length and explore the ideal of polynomials in variables with complex coefficients which vanish on the set . After setting up the basic theory, we investigate two parameters related to this ideal: is the smallest degree of a non-trivial polynomial in the ideal and is the smallest integer such that is generated by a set of polynomials of degree at most . We first prove the general bounds . Examining important families of examples, we find that, for symmetric 2-designs and Steiner systems, we have . But we expect to be closer to for less structured designs and we indicate this by constructing infinitely many triple systems satisfying .
Cite
@article{arxiv.1803.04931,
title = {A polynomial ideal associated to any $t$-$(v,k,\lambda)$ design},
author = {William J. Martin and Douglas R. Stinson},
journal= {arXiv preprint arXiv:1803.04931},
year = {2018}
}
Comments
26 pages, 1 figure