A Maximal Algebra.
A non-Banach in-convex algebra all of whose closed commutative subalgebras are Banach algebras.
We construct two examples of complete multiplicatively convex algebras with the property that all their maximal commutative subalgebras and consequently all commutative closed subalgebras are Banach algebras. One of them is non-metrizable and the other is metrizable and non-Banach. This solves Problems 12-16 and 22-24 of [7].
A note on minimal envelopes of Douglas algebras, minimal support sets, and restricted Douglas algebras.
A semitopological algebra without proper closed subalgebras
To Czesław Ryll-Nardzewski on his 70th birthday
A theorem concerning Ditkin's condition
Algèbres de fonctions analytiques dans le disque
An upper bound for the distance to finitely generated ideals in Douglas algebras
Let f be a function in the Douglas algebra A and let I be a finitely generated ideal in A. We give an estimate for the distance from f to I that allows us to generalize a result obtained by Bourgain for to arbitrary Douglas algebras.
Associative and Lie subalgebras of finite codimension
Ball proximinality of closed * subalgebras in C(Q)
The notion of ball proximinality and the strong ball proximinality were recently introduced in [2]. We prove that a closed * subalgebra A of C(Q) is strongly ball proximinal in C(Q) and the metric projection from C(Q), onto the closed unit ball of A, is Hausdorff metric continuous and hence has continuous selection.
Characterizations of amenable representations of compact groups
Let G be a locally compact group and let π be a unitary representation. We study amenability and H-amenability of π in terms of the weak closure of (π ⊗ π)(G) and factorization properties of associated coefficient subspaces (or subalgebras) in B(G). By applying these results, we obtain some new characterizations of amenable groups.
Compact Groups Operating on Banach Algebras.
Decompositions of operator-valued representations of function algebras
Die erzeugte Algebra eines Markov-Verbandsoperators in C(X).
Dual spaces and translation invariant means on group von Neumann algebras
Let G be a locally compact group. Its dual space, G*, is the set of all extreme points of the set of normalized continuous positive definite functions of G. In the early 1970s, Granirer and Rudin proved independently that if G is amenable as discrete, then G is discrete if and only if all the translation invariant means on are topologically invariant. In this paper, we define and study G*-translation operators on VN(G) via G* and investigate the problem of the existence of G*-translation invariant...
Extension of algebra norms and applications
Extensions of topological algebras.
Function algebras on the interval and circle
Holomorphically Closed Algebras of Analytic Functions.
Invariant subspaces on open Riemann surfaces
Let be a hyperbolic Riemann surface, a harmonic measure supported on the Martin boundary of , and the subalgebra of consisting of the boundary values of bounded analytic functions on . This paper gives a complete classification of the closed -submodules of , (weakly closed, if , when is regular and admits a sufficiently large family of bounded multiplicative analytic functions satisfying an approximation condition. It also gives, as a corollary, a corresponding result for the Hardy...
Invariant subspaces on open Riemann surfaces. II
We considerably improve our earlier results [Ann. Inst. Fourier, 24-4 (1974] concerning Cauchy-Read’s theorems, convergence of Green lines, and the structure of invariant subspaces for a class of hyperbolic Riemann surfaces.