dc.contributor.author Bernhard, Schmidt. dc.date.accessioned 2009-08-11T03:07:57Z dc.date.available 2009-08-11T03:07:57Z dc.date.copyright 1999 en_US dc.date.issued 1999 dc.identifier.citation Bernhard, S. (1999). Williamson matrices and a conjecture of Ito's. Journal of designs codes and cryptography, 17(1-3), 61-68. en_US dc.identifier.issn 0925-1022 en_US dc.identifier.uri http://hdl.handle.net/10220/6030 dc.description.abstract We point out an interesting connection between Williamson matrices and relative difference sets in nonabelian groups. As a consequence, we are able to show that there are relative (4t,2,4t,2t)-difference sets in the dicyclic groups Q_{8t}=\la a,b|a^{4t}=b^4=1, a^{2t}=b^2, b^{-1}ab=a^{-1}\ra for all t of the form t=2^a\cdot 10^b \cdot 26^c \cdot m with a,b,c\ge 0, m\equiv 1\ (\mod 2), whenever 2m-1 or 4m-1 is a prime power or there is a Williamson matrix over \Z_m. This gives further support to an important conjecture of Ito IT5 which asserts that there are relative (4t,2,4t,2t)-difference sets in Q_{8t} for every positive integer t. We also give simpler alternative constructions for relative (4t,2,4t,2t) -difference sets in Q_{8t} for all t such that 2t-1 or 4t-1 is a prime power. Relative difference sets in Q_{8t} with these parameters had previously been obtained by Ito IT1. Finally, we verify Ito‘s conjecture for all t\le 46. en_US dc.format.extent 11 p. en_US dc.language.iso en en_US dc.relation.ispartofseries Journal of designs codes and cryptography. en_US dc.rights Designs codes and cryptography © copyright 1999 Springer Netherlands. The journal's website is located at http://www.springerlink.com/content/m70j6m607k1630g2. en_US dc.subject DRNTU::Science::Mathematics::Discrete mathematics::Combinatorics dc.title Williamson matrices and a conjecture of Ito's en_US dc.type Journal Article dc.contributor.school School of Physical and Mathematical Sciences en_US dc.identifier.doi http://dx.doi.org/10.1023/A:1008398319853 dc.description.version Accepted version en_US
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