Thời gian: 14 Thứ Sáu ngày 17/5/2024

Địa điểm: Phòng 612 Nhà A6

Abstract: In this talk, after reviewing some basic properties of *-algebra of mixed polynomials, moment matrices of a positive linear operator in a link with flat extension techniques, we will give a sufficient and necessary condition for a sum of squared magnitude of mixed polynomials to be a sum of squared magnitude of usual complex polynomials. Some related problems will be discussed including an analogue to Hilbert's 17th problem for mixed polynomials.