Results 81 to 90 of about 5,376,972 (220)

Geometry of essential matrix ranges and the Smith–Ward problem for operator systems

open access: yesBulletin of the London Mathematical Society, Volume 58, Issue 9, September 2026.
Abstract A d$d$‐tuple of bounded linear selfadjoint operators acting on an infinite‐dimensional separable Hilbert space is said to have the Smith–Ward property if the identity map of the image of the operator system in the Calkin algebra has a completely positive lift.
Douglas Farenick   +2 more
wiley   +1 more source

A new semigroup technique in poisson approximation [PDF]

open access: yes, 1989
Publisher's, offprint versionWe present a unified and self-contained approach to Poisson approximation problems for independent Bernoulli summands with respect to several metrics by a general semigroup technique, expanding and completing earlier work on ...
Pfeifer, Dietmar   +2 more
core   +1 more source

Boundary controllability of impulsive nonlinear fractional delay integro-differential system

open access: yesCogent Engineering, 2016
By using the strongly continuous semigroup theory and the Banach contraction principle, we study the boundary controllability of time varying delay impulsive nonlinear fractional integrodifferential system in Banach spaces.
Hamdy M. Ahmed
doaj   +1 more source

Geometric inverse semigroup theory: a note on the Milnor–Schwarz lemma for inverse monoids

open access: yesBulletin of the London Mathematical Society, Volume 58, Issue 9, September 2026.
Abstract We generalise the Milnor–Schwarz lemma to inverse monoids acting on presheaves of geodesic metric spaces. We provide two proofs of this fact: one only uses elementary techniques, inspired by the arguments for group actions on metric spaces; the other involves a version of the Vietoris–Rips complex, and builds on work of Chung–Martínez–Szakács.
Giorgio Mangioni, Francesco Tesolin
wiley   +1 more source

A spectral mapping theorem for evolution semigroups on asymptotically almost periodic functions defined on the half line

open access: yesElectronic Journal of Differential Equations, 2002
We prove that the evolution semigroup on $AAP_0(mathbb{R}_+, X)$ is strongly continuous. Then we prove some properties of the generator of this evolution semigroup and show some applications in the theory of inequalities.
Constantin Buse
doaj  

Ordered Semigroups Based on ∈,∈∨qkδ-Fuzzy Ideals

open access: yesAdvances in Fuzzy Systems, 2018
A new trend of using fuzzy algebraic structures in various applied sciences is becoming a central focus due to the accuracy and nondecoding nature. The aim of the present paper is to develop a new type of fuzzy subsystem of an ordered semigroup S.
Faiz Muhammad Khan   +3 more
doaj   +1 more source

Uniqueness problem for accretive Schrödinger operators with complex singular coefficients

open access: yesBulletin of the London Mathematical Society, Volume 58, Issue 9, September 2026.
Abstract This paper studies the uniqueness problem for the one‐dimensional Schrödinger operator associated with the formal differential expression l[u]=−u′′+qu+i[(ru)′+ru′]$l[u] =-u^{\prime \prime }+qu + i[(ru)^{\prime }+ru^{\prime }] $ in the complex Hilbert space L2(R)$L^{2}(\mathbb {R})$.
Vladimir Mikhailets, Volodymyr Molyboga
wiley   +1 more source

Cartwright–Sturmfels Hilbert schemes

open access: yesJournal of the London Mathematical Society, Volume 114, Issue 3, September 2026.
Abstract Let S$S$ be the Cox ring of a product of r$r$ projective spaces. In this paper, we study the Cartwright–Sturmfels Hilbert schemes of S$S$, which are multigraded Hilbert schemes that parameterize only radical ideals. Our main result shows that these Hilbert schemes are always smooth and irreducible if the Picard rank r$r$ is at most 2.
Ritvik Ramkumar, Alessio Sammartano
wiley   +1 more source

Unary FA-presentable semigroups [PDF]

open access: yes, 2012
Automatic presentations, also called FA-presentations, were introduced to extend nite model theory to innite structures whilst retaining the solubility of interesting decision problems.
Cain, Alan James   +2 more
core   +1 more source

On the Presentation and Cayley Graph of the Bruck–Reilly Idealization Semigroup

open access: yesJournal of Mathematics
Transferring constructions between different algebraic structures often reveals deep connections and enables the application of techniques from one theory to another.
Suha Wazzan   +2 more
doaj   +1 more source

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