Low-Discrepancy Point Sets.
We prove several results concerning the existence of low-discrepancy point sets with respect to an arbitrary non-uniform measure μ on the d-dimensional unit cube. We improve a theorem of Beck, by showing that for any d ≥ 1, N ≥ 1, and any non-negative, normalized Borel measure μ on there exists a point set whose star-discrepancy with respect to μ is of order . For the proof we use a theorem of Banaszczyk concerning the balancing of vectors, which implies an upper bound for the linear discrepancy...
Let be a square-free positive integer and be the class number of the real quadratic field We give an explicit lower bound for , where . Ankeny and Chowla proved that if is a natural number and is a square-free integer, then whenever . Applying our lower bounds, we show that there does not exist any natural number such that . We also obtain a similar result for the family . As another application, we deduce some criteria for a class group of prime power order to be cyclic.
We study representation functions of asymptotic additive bases and more general subsets of ℕ (sets with few nonrepresentable numbers). We prove that if ℕ∖(A+A) has sufficiently small upper density (as in the case of asymptotic bases) then there are infinitely many numbers with more than five representations in A+A, counting order.
We show that the large sieve is optimal for almost all exponential sums.
After a brief exposition of the state-of-art of research on the (Euclidean) simultaneous Diophantine approximation constants , new lower bounds are deduced for and .