scholarly journals Barbashin conditions for uniform instability of evolution operators

2021 ◽  
Vol 66 (2) ◽  
pp. 297-305
Author(s):  
Mihail Megan ◽  
Rovana Boruga (Toma)
Keyword(s):  
Evolution Operators ◽  
Exponential Instability ◽  
Characterization Theorems

"The aim of the present paper is to give some characterization theorems of Barbashin type for the uniform exponential instability and uniform polynomial instability behavior of evolution operators. Also, some examples which illustrate the connections between the concepts presented are given."

scholarly journals Polynomial instability of evolution operators in Banach spaces

2013 ◽  
Vol 29 (1) ◽  
pp. 77-83
Author(s):  
MAGDA LUMINITA RAMNEANTU ◽  
◽  
MIHAIL MEGAN ◽  
TRAIAN CEAUSU ◽  
◽  
...  
Keyword(s):  
Banach Spaces ◽  
Evolution Operators ◽  
Exponential Instability

In this paper we consider two concepts of polynomial instability for evolution operators in Banach spaces. Our approach is based on the extension of techniques for exponential instability to the case of polynomial instability. The obtained results are generalizations of some theorems about uniform and nonuniform exponential instability.

Malcev product of superabundant semigroups and its subsemigroups

2016 ◽  
Vol 09 (03) ◽  
pp. 1650058 ◽  
Author(s):  
X. M. Ren ◽  
J. Xue ◽  
K. P. Shum
Keyword(s):  
Malcev Product ◽  
Characterization Theorems

We use Malcev product of semigroups satisfying some axiomatic conditions to describe the structure of superabundant semigroups and some of its subclasses. Some characterization theorems of these kinds of semigroups are given.

scholarly journals Lightlike Hypersurfaces of Indefinite Generalized Sasakian Space Forms

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Dae Ho Jin
Keyword(s):  
Vector Field ◽  
Space Form ◽  
Sasakian Manifold ◽  
Sasakian Space Form ◽  
Space Forms ◽  
Sasakian Structure ◽  
Sasakian Space Forms ◽  
Generalized Sasakian Space Form ◽  
Characterization Theorems ◽  
Lightlike Hypersurfaces

We study lightlike hypersurfacesMof an indefinite generalized Sasakian space formM-(f1,f2,f3), with indefinite trans-Sasakian structure of type(α,β), subject to the condition that the structure vector field ofM-is tangent toM. First we study the general theory for lightlike hypersurfaces of indefinite trans-Sasakian manifold of type(α,β). Next we prove several characterization theorems for lightlike hypersurfaces of an indefinite generalized Sasakian space form.

Left semi-perfect abundant semi-groups of type W

2005 ◽  
Vol 135 (3) ◽  
pp. 603-614 ◽  
Author(s):  
Xiaojiang Guo ◽  
K. P. Shum
Keyword(s):  
Normal Band ◽  
Semi Group ◽  
Characterization Theorems

We call a quasi-adequate semi-group whose set of idempotents forms a left [right] quasi-normal band a left [right] semi-perfect abundant semi-group. After obtaining some characterization theorems of such quasi-adequate semi-groups, we establish a structure for left [right] semi-perfect abundant semi-groups of type W. Our results generalize and strengthen the results of El-Qallali and Fountain on quasi-adequate semi-groups.

Sign in / Sign up

Export Citation Format

Share Document