Designs in finite classical polar spaces

Fuente: arXiv
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Main Authors: Kiermaier, Michael, Schmidt, Kai-Uwe, Wassermann, Alfred
Format: Preprint
Published: 2024
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author Kiermaier, Michael
Schmidt, Kai-Uwe
Wassermann, Alfred
author_facet Kiermaier, Michael
Schmidt, Kai-Uwe
Wassermann, Alfred
contents Combinatorial designs have been studied for nearly 200 years. Fifty years ago, Cameron, Delsarte, and Ray-Chaudhury started investigating their q-analogs, also known as subspace designs or designs over finite fields. Designs can be defined analogously in finite classical polar spaces, too. The definition includes the m-regular systems from projective geometry as the special case where the blocks are generators of the polar space. The first nontrivial such designs for t > 1 were found by De Bruyn and Vanhove in 2012, and some more designs appeared recently in the PhD thesis of Lansdown. In this article, we investigate the theory of classical and subspace designs for applicability to designs in polar spaces, explicitly allowing arbitrary block dimensions. In this way, we obtain divisibility conditions on the parameters, derived and residual designs, intersection numbers and an analog of Fisher's inequality. We classify the parameters of symmetric designs. Furthermore, we conduct a computer search to construct designs of strength t=2, resulting in designs for more than 140 previously unknown parameter sets in various classical polar spaces over GF(2) and GF(3).
format Preprint
id arxiv_https___arxiv_org_abs_2403_11188
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Designs in finite classical polar spaces
Kiermaier, Michael
Schmidt, Kai-Uwe
Wassermann, Alfred
Combinatorics
Combinatorial designs have been studied for nearly 200 years. Fifty years ago, Cameron, Delsarte, and Ray-Chaudhury started investigating their q-analogs, also known as subspace designs or designs over finite fields. Designs can be defined analogously in finite classical polar spaces, too. The definition includes the m-regular systems from projective geometry as the special case where the blocks are generators of the polar space. The first nontrivial such designs for t > 1 were found by De Bruyn and Vanhove in 2012, and some more designs appeared recently in the PhD thesis of Lansdown. In this article, we investigate the theory of classical and subspace designs for applicability to designs in polar spaces, explicitly allowing arbitrary block dimensions. In this way, we obtain divisibility conditions on the parameters, derived and residual designs, intersection numbers and an analog of Fisher's inequality. We classify the parameters of symmetric designs. Furthermore, we conduct a computer search to construct designs of strength t=2, resulting in designs for more than 140 previously unknown parameter sets in various classical polar spaces over GF(2) and GF(3).
title Designs in finite classical polar spaces
topic Combinatorics
url https://arxiv.org/abs/2403.11188