Equiangular line systems and switching classes containing regular graphs
Greaves, Gary Royden Watson
Date of Issue2017
School of Physical and Mathematical Sciences
We develop the theory of equiangular lines in Euclidean spaces. Our focus is on the question of when a Seidel matrix having precisely three distinct eigenvalues has a regular graph in its switching class. We make some progress towards an answer to this question by finding some necessary conditions and some sufficient conditions. Furthermore we show that the cardinality of an equiangular line system in 18 dimensional Euclidean space is at most 60.
Linear Algebra and its Applications
© 2017 Elsevier Inc. All rights reserved. This paper was published in Linear Algebra and Its Applications and is made available with permission of Elsevier Inc.