Strong External Difference Families and Classification of $α$-valuations

Fuente: arXiv
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Main Authors: Kreher, Donald L., Paterson, Maura B., Stinson, Douglas R.
Format: Preprint
Published: 2024
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author Kreher, Donald L.
Paterson, Maura B.
Stinson, Douglas R.
author_facet Kreher, Donald L.
Paterson, Maura B.
Stinson, Douglas R.
contents One method of constructing $(a^2+1, 2,a, 1)$-SEDFs (i.e., strong external difference families) in $\mathbb{Z}_{a^2+1}$ makes use of $α$-valuations of complete bipartite graphs $K_{a,a}$. We explore this approach and we provide a classification theorem which shows that all such $α$-valuations can be constructed recursively via a sequence of ``blow-up'' operations. We also enumerate all $(a^2+1, 2,a, 1)$-SEDFs in $\mathbb{Z}_{a^2+1}$ for $a \leq 14$ and we show that all these SEDFs are equivalent to $α$-valuations via affine transformations. Whether this holds for all $a > 14$ as well is an interesting open problem. We also study SEDFs in dihedral groups, where we show that two known constructions are equivalent.
format Preprint
id arxiv_https___arxiv_org_abs_2406_09075
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Strong External Difference Families and Classification of $α$-valuations
Kreher, Donald L.
Paterson, Maura B.
Stinson, Douglas R.
Combinatorics
05B10, 05C78
One method of constructing $(a^2+1, 2,a, 1)$-SEDFs (i.e., strong external difference families) in $\mathbb{Z}_{a^2+1}$ makes use of $α$-valuations of complete bipartite graphs $K_{a,a}$. We explore this approach and we provide a classification theorem which shows that all such $α$-valuations can be constructed recursively via a sequence of ``blow-up'' operations. We also enumerate all $(a^2+1, 2,a, 1)$-SEDFs in $\mathbb{Z}_{a^2+1}$ for $a \leq 14$ and we show that all these SEDFs are equivalent to $α$-valuations via affine transformations. Whether this holds for all $a > 14$ as well is an interesting open problem. We also study SEDFs in dihedral groups, where we show that two known constructions are equivalent.
title Strong External Difference Families and Classification of $α$-valuations
topic Combinatorics
05B10, 05C78
url https://arxiv.org/abs/2406.09075