Speaker : Dr. Wei-Hsuan Yu(University of Mariland)
Title : A note on spherical two-distance sets
Time : 2012-02-17 (Fri) 15:30 - 17:00
Place : Seminar Room 722, Institute of Mathematics (NTU Campus)
Abstract: A spherical two-distance set is a finite collection of unit vectors in R^n such that the set of distances between any two distinct vectors has cardinality two. O.R. Musin used Delsarte’s linear programming method to prove the result when 7 ≤ n ≤ 39, except n=23. We use the semi-definite programming and sum of square method (SOS) to compute improved estimates of the maximum size of spherical two-distance sets. Exact answers are found for dimensions n = 23 and 40 ≤ n ≤ 94, where previous results gave divergent bounds.