In this paper the characterization as convolution operators of filters sending finite energy signals to bounded signals is used to prove several theoretical results concerning the distance betweenâ€¦ (More)

In this paper we characterize the approximation schemes tha t atisfy Shapiroâ€™s theorem and we use this result for several classical approximation proces ses. In particular, we study approximation ofâ€¦ (More)

Given a set of nonnegative real numbers Î›= {Î»i}i=0, a Î›-polynomial (or MÃ¼ntz polynomial) is a function of the form p(x)=ni=0 aizi (nâˆˆN). We denote by Î (Î›) the space of Î›-polynomials and by Î Z(Î›) :=â€¦ (More)

If a (non-constant) polynomial has no zero, then a certain Riemannian metric is constructed on the two dimensional sphere. Several geometric arguments are then shown to contradict this fact. M.S.C.â€¦ (More)

In this paper we obtain several tight bounds on different types of alliance numbers of a graph, namely (global) defensive alliance number, global offensive alliance number and global dual allianceâ€¦ (More)

The main goal of this note is to give a new elementary proof of the Fundamental Theorem of Algebra. This proof is based on the use of the well known Gelfand-Mazur Theorem.

We present an elementary proof of a general version of Montelâ€™s theorem in several variables which is based on the use of tensor product polynomial interpolation. We also prove a Montel-Popoviciuâ€™sâ€¦ (More)