 Abstract | After our introduction in Chapter 1, we consider van der Corput's lemma in Chapter 2. We find the nodes that minimize divided differences, and use these to find the sharp constant in a related sublevel set estimate. We go on to find the sharp constant in the first instance of the van der Corput lemma using a complex mean value theorem for integrals. With these bounds we improve the constant in the general van der Corput lemma, so that it is asymptotically sharp.
In Chapter 3 we review the p-adic numbers and some results from Fourier analysis over the p-adics. In Chapter 4 we prove a p-adic version of van der Corput's lemma for polynomials, opening the way for the study of oscillatory integrals over the p-adics. In Chapter 5 we apply this result to bound maximal averages. We show that maximal averages over curves defined by p-adic polynomials are Lq bounded, where 1<q<infinity
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