scholarly journals History, Developments and Open Problems on Approximation Properties

Mathematics ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 1117
Author(s):  
Ju Myung Kim ◽  
Bentuo Zheng

In this paper, we give a comprehensive review of the classical approximation property. Then, we present some important results on modern variants, such as the weak bounded approximation property, the strong approximation property and p-approximation property. Most recent progress on E-approximation property and open problems are discussed at the end.

2022 ◽  
Author(s):  
◽  
Long Qian

<p><b>We investigate the geometry of effective Banach spaces, namely a sequenceof approximation properties that lies in between a Banach space having a basis and the approximation property.</b></p> <p>We establish some upper bounds on suchproperties, as well as proving some arithmetical lower bounds. Unfortunately,the upper bounds obtained in some cases are far away from the lower bound.</p> <p>However, we will show that much tighter bounds will require genuinely newconstructions, and resolve long-standing open problems in Banach space theory.</p> <p>We also investigate the effectivisations of certain classical theorems in Banachspaces.</p>


2011 ◽  
Vol 03 (01n02) ◽  
pp. 229-249 ◽  
Author(s):  
PANAYOT S. VASSILEVSKI

We give an overview of a number of algebraic multigrid methods targeting finite element discretization problems. The focus is on the properties of the constructed hierarchy of coarse spaces that guarantee (two-grid) convergence. In particular, a necessary condition known as "weak approximation property," and a sufficient one, referred to as "strong approximation property," are discussed. Their role in proving convergence of the TG method (as iterative method) and also on the approximation properties of the algebraic mottigrid (AMG) coarse spaces if used as discretization tool is pointed out. Some preliminary numerical results illustrating the latter aspect are also reported.


2022 ◽  
Author(s):  
◽  
Long Qian

<p><b>We investigate the geometry of effective Banach spaces, namely a sequenceof approximation properties that lies in between a Banach space having a basis and the approximation property.</b></p> <p>We establish some upper bounds on suchproperties, as well as proving some arithmetical lower bounds. Unfortunately,the upper bounds obtained in some cases are far away from the lower bound.</p> <p>However, we will show that much tighter bounds will require genuinely newconstructions, and resolve long-standing open problems in Banach space theory.</p> <p>We also investigate the effectivisations of certain classical theorems in Banachspaces.</p>


2021 ◽  
Vol 6 (4) ◽  
pp. 754-787
Author(s):  
Sanjeev Dhawan ◽  
Vishal Kumar ◽  
Pankaj S. Girase ◽  
Sithabile Mokoena ◽  
Rajshekhar Karpoormath

Author(s):  
Henrik Ueberschär

This survey article deals with a delta potential—also known as a point scatterer—on flat two- and three-dimensional tori. We introduce the main conjectures regarding the spectral and wave function statistics of this model in the so-called weak and strong coupling regimes. We report on recent progress as well as a number of open problems in this field.


2018 ◽  
Vol 82 ◽  
pp. 1990-2004 ◽  
Author(s):  
Bablu K. Ghosh ◽  
Chadwin N.J. Weoi ◽  
Aminul Islam ◽  
Swapan K. Ghosh

2000 ◽  
Vol 176 ◽  
pp. 408-414
Author(s):  
G. Handler

AbstractAn overview of recent progress in the research on δ Scuti stars is given. Some intriguing results and open problems are pointed out, and some ideas for future investigations are provided.


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