Let AR denote the set of functions from the disk algebra having real Fourier coefficients. Generalizing a result of A. Quadrat we show that every unstabilizable multi-input multi-output plant is as close as we want to a stabilizable multi-input multi-output plant in the product topology.

We give an example of a non-compact, locally compact group G such that its Fourier–Stieltjes algebra B(G) is operator amenable. Furthermore, we characterize those G for which A * (G)—the spine of B(G) as introduced by M. Ilie and the second named author—is operator amenable and show that A * (G) is operator weakly amenable for each G.

We show that for a Jacobi operator with coefficients whose (j + 1)’th moments are summable the j’th derivative of the scattering matrix is in the Wiener algebra of functions with summable Fourier coefficients. We use this result to improve the known dispersive estimates with integrable time decay for the time dependent Jacobi equation in the resonant case.

Group elements of SU(2) are expressed in closed form as finite polynomials of the Lie algebra generators, for all definite spin representations of the rotation group. The simple explicit result exhibits connections between group theory, combinatorics, and Fourier analysis, especially in the large spin limit. Salient intuitive features of the formula are illustrated and discussed.

Two new methods for computing with hypergeometric distributions on lattice points are presented. One uses Fourier analysis, and the other uses Gröbner bases in the Weyl algebra. Both are very general and apply to log-linear models that are graphical or non-graphical.

We show that for a one-dimensional Schrödinger operator with a potential, whose (j + 1)-th moment is integrable, the j-th derivative of the scattering matrix is in the Wiener algebra of functions with integrable Fourier transforms. We use this result to improve the known dispersive estimates with integrable time decay for the one-dimensional Schrödinger equation in the resonant case.

We estimate the norms of many matrix coefficients of irreducible uniformly bounded representations of SL(2, R) as completely bounded multipliers of the Fourier algebra. Our results suggest that the known inequality relating the uniformly bounded norm of a representation and the completely bounded norm of its coefficients may not be optimal.

We give an example of a non-compact, locally compact group G such that its Fourier–Stieltjes algebra B(G) is operator amenable. Furthermore, we characterize those G for which A * (G)—the spine of B(G) as introduced by M. Ilie and the second named author—is operator amenable and show that A * (G) is operator weakly amenable for each G.

We introduce noncommutative extensions of the Fourier transform of probability measures and its logarithm in the algebra A(S) of complex-valued functions on the free semigroup on two generators S = FS({z,w}). First, to given probability measures μ, ν whose all moments are finite, we associate states μ̂, ν̂ on the unital free *-bialgebra (B, ǫ,∆) on two self-adjoint generators X,X ′ and a projecti...

In multi-dimensional signal processing the Cliiord Fourier transform (CFT or in the 2-D case: quater-nionic Fourier transform/QFT) is a consequent extension of the complex valued Fourier transform. Hence, we need a fast algorithm in order to compute the transform in practical applications. Since the CFT is based on a corresponding Cliiord algebra (CA) and CAs are not commutative in general, we ...