Inequivalent Hadamard matrices of order 2n constructed from Hadamard matrices of order n

Georgiou, S; Kotsireas, I; Koukouvinos, C

dc.contributor.author	Georgiou, S	en
dc.contributor.author	Kotsireas, I	en
dc.contributor.author	Koukouvinos, C	en
dc.date.accessioned	2014-03-01T01:56:19Z
dc.date.available	2014-03-01T01:56:19Z
dc.date.issued	2007	en
dc.identifier.issn	08353026	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/28058
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-77949913150&partnerID=40&md5=4e760503bdaf7987ecf8d58ed7dcb699	en
dc.subject	Doubling construction	en
dc.subject	Hadamard matrices	en
dc.subject	Inequivalence	en
dc.subject	Profile criterion	en
dc.subject.other	Hadamard matrices	en
dc.subject.other	Magma code segment	en
dc.subject.other	Combinatorial mathematics	en
dc.subject.other	Heuristic methods	en
dc.subject.other	Number theory	en
dc.subject.other	Matrix algebra	en
dc.title	Inequivalent Hadamard matrices of order 2n constructed from Hadamard matrices of order n	en
heal.type	journalArticle	en
heal.publicationDate	2007	en
heal.abstract	In this paper we establish a doubling method to construct ino equivalent Hadamard matrices of order 2n, from Hadamard matrices of order n. Our doubling method uses heavily the symmetric group Sn, where n is the order of a Hadamard matrix. We improve the efficiency of the method by introducing some group-theoretical heuristics. Using the doubling method in conjunction with the standard 4-row profile criterion, we have constructed several millions of new inequivalent Hadamard matrices of orders 48, 56, 64, 72, 80, 88, 96 and several hundreds of inequivalent Hadamard matrices of orders 672 and 856. The Magma code segments, included in this paper, allow one to compute many more inequivalent Hadamard matrices of the above orders and all other orders of the form 8t.	en
heal.journalName	Journal of Combinatorial Mathematics and Combinatorial Computing	en
dc.identifier.volume	63	en
dc.identifier.spage	65	en
dc.identifier.epage	79	en