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JOURNAL OF
ALGEBRAIC
COMBINATORICS

  Editors-in-chief: C. A. Athanasiadis, T. Lam, A. Munemasa, H. Van Maldeghem
ISSN 0925-9899 (print) • ISSN 1572-9192 (electronic)
 

Cocyclic Development of Designs

K.J. Horadam and W. de Launey

DOI: 10.1023/A:1022403732401

Abstract

We present the basic theory of cocyclic development of designs, in which group development over a finite group G is modified by the action of a cocycle defined on G \times  G. Negacyclic and ohgr-cyclic development are both special cases of cocyclic development.
Techniques of design construction using the group ring, arising from difference set methods, also apply to cocyclic designs. Important classes of Hadamard matrices and generalized weighing matrices are cocyclic.

Pages: 267–290

Keywords: orthogonal design; Hadamard matrix; difference set; group development; negacyclic development; $ohgr$-cyclic development; cocycle; cohomology group; homology group; extension group

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