Kolloquien und Oberseminare Übersicht Detail

Vortragende Person/Vortragende Personen:
Philipp di Dio

We study K-positivity preserves T:R[x_1,...,x_n]->R[x_1,...,x_n] with constant coefficients and K a subset of R^n; especially their generators A, i.e., T = e^A. We completely describe the set of generators A such that exp(tA) is a positivity preserver for all t geq 0. The complete description of generators of [0,\infty)-positivity preservers is given. We give an example of a strange positivity action which on [0,\infty) maps odd non-negative polynomials to odd non-negative polynomials but even non-negative polynomials are mapped to non-negative functions which are not polynomials. We introduce the concept of a convolution of (moment) sequences.