On the (Fourier analytic) Sidon constant of 0,1,2,3
Abstract
This constant is the maximum of the sum |c0|+|c1|+|c2|+|c3| of the moduli of the coefficients of a trigonometric polynomial c0+c1eit+c2e2it+c3e3it bounded by 1. Its value is still unknown, but I will present some ideas on how to compute it and describe a distinguished torus of extremal functions.
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