The search session has expired. Please query the service again.

The search session has expired. Please query the service again.

Displaying 5201 – 5220 of 13227

Showing per page

Korovkin theory in normed algebras

Ferdinand Beckhoff (1991)

Studia Mathematica

If A is a normed power-associative complex algebra such that the selfadjoint part is normally ordered with respect to some order, then the Korovkin closure (see the introduction for definitions) of T ∪ {t* ∘ t| t ∈ T} contains J*(T) for any subset T of A. This can be applied to C*-algebras, minimal norm ideals on a Hilbert space, and to H*-algebras. For bounded H*-algebras and dual C*-algebras there is even equality. This answers a question posed in [1].

Köthe coechelon spaces as locally convex algebras

José Bonet, Paweł Domański (2010)

Studia Mathematica

We study those Köthe coechelon sequence spaces k p ( V ) , 1 ≤ p ≤ ∞ or p = 0, which are locally convex (Riesz) algebras for pointwise multiplication. We characterize in terms of the matrix V = (vₙ)ₙ when an algebra k p ( V ) is unital, locally m-convex, a -algebra, has a continuous (quasi)-inverse, all entire functions act on it or some transcendental entire functions act on it. It is proved that all multiplicative functionals are continuous and a precise description of all regular and all degenerate maximal ideals...

Köthe spaces modeled on spaces of C functions

Mefharet Kocatepe, Viacheslav Zahariuta (1996)

Studia Mathematica

The isomorphic classification problem for the Köthe models of some C function spaces is considered. By making use of some interpolative neighborhoods which are related to the linear topological invariant D φ and other invariants related to the “quantity” characteristics of the space, a necessary condition for the isomorphism of two such spaces is proved. As applications, it is shown that some pairs of spaces which have the same interpolation property D φ are not isomorphic.

K-theory of Boutet de Monvel's algebra

Severino T. Melo, Ryszard Nest, Elmar Schrohe (2003)

Banach Center Publications

We consider the norm closure 𝔄 of the algebra of all operators of order and class zero in Boutet de Monvel's calculus on a compact manifold X with boundary ∂X. Assuming that all connected components of X have nonempty boundary, we show that K₁(𝔄) ≃ K₁(C(X)) ⊕ ker χ, where χ: K₀(C₀(T*Ẋ)) → ℤ is the topological index, T*Ẋ denoting the cotangent bundle of the interior. Also K₀(𝔄) is topologically determined. In case ∂X has torsion free K-theory, we get K₀(𝔄) ≃ K₀(C(X)) ⊕ K₁(C₀(T*Ẋ)).

Currently displaying 5201 – 5220 of 13227