Fundamental solutions of pseudo-differential operators over p-adic fields

We show the existence of fundamental solutions for p-adic pseudo-differential operators with polynomial symbols.Comment: To appear in Rend. Sem. Mat. Univ. Padov

Exponential Sums Along p-adic Curves

Let K be a p-adic field, R the valuation ring of K, and P the maximal ideal of R. Let $Y subseteq R^{2}$ be a non-singular closed curve, and Y_{m} its image in R/P^{m} times R/P^{m}, i.e. the reduction modulo P^{m} of Y. We denote by Psi an standard additive character on K. In this paper we discuss the estimation of exponential sums of type S_{m}(z,Psi,Y,g):= sum\limits_{x in Y_{m}} Psi(zg(x)), with z in K, and g a polynomial function on Y. We show that if the p-adic absolute value of z is big enough then the complex absolute value of S_{m}(z,Psi,Y,g) is O(q^{m(1-beta(f,g))}), for a positive constant beta(f,g) satisfying 0<beta(f,g)<1.Comment: 9 pages. Accepted in Finite Fields and Their Application