Equiangular line systems and switching classes containing regular graphs

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 a...

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Bibliographic Details
Main Author: Greaves, Gary Royden Watson
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2019
Subjects:
Online Access:https://hdl.handle.net/10356/104621
http://hdl.handle.net/10220/47869
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Institution: Nanyang Technological University
Language: English
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Summary: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.