Sets of Complex Unit Vectors with Two Angles and Distance-Regular Graphs
Abstract
We study 0,α-sets, which are sets of unit vectors of Cm in which any two distinct vectors have angle 0 or α. We investigate some distance-regular graphs that provide new constructions of 0,α-sets using a method by Godsil and Roy. We prove bounds for the sizes of 0,α-sets of flat vectors, and characterize all the distance-regular graphs that yield 0,α-sets meeting the bounds at equality.
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