Extending Multipliers from Semigroups

Extending Multipliers from Semigroups

A multiplier on a normal subsemigroup of a group can be extended to a multiplier on the group. This is used to show that normal cancellative semigroups have the same second cohomology as the group they generate, generalising earlier results of Arveson, ChernofF, and Dinh. The main tool is a dilation theorem for isometric multiplier representations of semigroups.

Extending Multipliers of the Fourier Algebra from a Subgroup

In this paper, we consider various extension problems associated with elements in the the closure with respect to either the multiplier norm or the completely bounded multiplier norm of the Fourier algebra of a locally compact group. In particular, we show that it is not always possible to extend an element in the closure with respect to the multiplier norm of the Fourier algebra of the free gr...

A Note on Extending Semicharacters on Semigroups

The purpose of this note is to give a necessary and sufficient condition for a semicharacter on a subsemigroup of a commutative semigroup G to be extendable to a semicharacter on G. A bounded complex function x on a semigroup G is called a semicharacter of G if x(x)9^0 for some xEG and x(xy) = x(%)x(y) ior all x, yEG. Semicharacters were introduced by Hewitt and Zuckerman [l] and in a slightly ...

SEMIGROUPS OF WELL-BOUNDED OFERATORS AND MULTIPLIERS by

From Forms to Semigroups

We present a review and some new results on form methods for generating holomorphic semigroups on Hilbert spaces. In particular, we explain how the notion of closability can be avoided. As examples we include the Stokes operator, the Black–Scholes equation, degenerate differential equations and the Dirichlet-to-Neumann operator. Mathematics Subject Classification (2000). Primary 47A07; Secondar...