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One-parameter semigroups in the convolution algebra of rapidly decreasing distributions

(2012)

Colloquium Mathematicae

The paper is devoted to infinitely differentiable one-parameter convolution semigroups in the convolution algebra C ' ( ; M m × m ) of matrix valued rapidly decreasing distributions on ℝⁿ. It is proved that G C ' ( ; M m × m ) is the generating distribution of an i.d.c.s. if and only if the operator t m × m - G on 1 + n satisfies the Petrovskiĭ condition for forward evolution. Some consequences are discussed.

One-sided division absolute valued algebras.

Ana Rodríguez Palacios (1992)

Publicacions Matemàtiques

We develop a structure theory for left divsion absolute valued algebras which shows, among other things, that the norm of such an algebra comes from an inner product. Moreover, we prove the existence of left division complete absolute valued algebras with left unit of arbitrary infinite hilbertian division and with the additional property that they have nonzero proper closed left ideals. Our construction involves results from the representation theory of the so called "Canonical Anticommutation...

One-weight weak type estimates for fractional and singular integrals in grand Lebesgue spaces

Vakhtang Kokilashvili, Alexander Meskhi (2014)

Banach Center Publications

We investigate weak type estimates for maximal functions, fractional and singular integrals in grand Lebesgue spaces. In particular, we show that for the one-weight weak type inequality it is necessary and sufficient that a weight function belongs to the appropriate Muckenhoupt class. The same problem is discussed for strong maximal functions, potentials and singular integrals with product kernels.

Open partial isometries and positivity in operator spaces

David P. Blecher, Matthew Neal (2007)

Studia Mathematica

We first study positivity in C*-modules using tripotents ( = partial isometries) which are what we call open. This is then used to study ordered operator spaces via an "ordered noncommutative Shilov boundary" which we introduce. This boundary satisfies the usual universal diagram/property of the noncommutative Shilov boundary, but with all the arrows completely positive. Because of their independent interest, we also systematically study open tripotents and their properties.

Open projections in operator algebras I: Comparison theory

David P. Blecher, Matthew Neal (2012)

Studia Mathematica

We begin a program of generalizing basic elements of the theory of comparison, equivalence, and subequivalence, of elements in C*-algebras, to the setting of more general algebras. In particular, we follow the recent lead of Lin, Ortega, Rørdam, and Thiel of studying these equivalences, etc., in terms of open projections or module isomorphisms. We also define and characterize a new class of inner ideals in operator algebras, and develop a matching theory of open partial isometries in operator ideals...

Open projections in operator algebras II: Compact projections

David P. Blecher, Matthew Neal (2012)

Studia Mathematica

We generalize some aspects of the theory of compact projections relative to a C*-algebra, to the setting of more general algebras. Our main result is that compact projections are the decreasing limits of 'peak projections', and in the separable case compact projections are just the peak projections. We also establish new forms of the noncommutative Urysohn lemma relative to an operator algebra, and we show that a projection is compact iff the associated face in the state space of the algebra is...

Open Subsets of LF-spaces

Kotaro Mine, Katsuro Sakai (2008)

Bulletin of the Polish Academy of Sciences. Mathematics

Let F = ind lim Fₙ be an infinite-dimensional LF-space with density dens F = τ ( ≥ ℵ ₀) such that some Fₙ is infinite-dimensional and dens Fₙ = τ. It is proved that every open subset of F is homeomorphic to the product of an ℓ₂(τ)-manifold and = i n d l i m (hence the product of an open subset of ℓ₂(τ) and ). As a consequence, any two open sets in F are homeomorphic if they have the same homotopy type.

Currently displaying 1761 – 1780 of 1952