1. CMB Online first
 Abrahamsen, Trond A.; Hájek, Petr; Nygaard, Olav; Troyanski, Stanimir L.

Strongly extreme points and approximation properties
We show that if $x$ is a strongly extreme point of a bounded closed
convex subset of a Banach space and the identity has a geometrically
and topologically good enough local approximation at $x$, then $x$
is already a denting point. It turns out that such an approximation
of the identity exists at any strongly extreme point of the unit
ball of a Banach space with the unconditional compact approximation
property. We also prove that every Banach space with a Schauder
basis can be equivalently renormed to satisfy the sufficient
conditions mentioned.
Keywords:denting point, strongly extreme point, unconditional compact approximation property Categories:46B20, 46B04 

2. CMB 2016 (vol 60 pp. 872)
 Xu, Xu; Zhu, Laiyi

Rational Function Operators from Poisson Integrals
In this paper, we construct two classes of rational function
operators by using the Poisson integrals of the function on the
whole real
axis. The convergence rates of the uniform and mean approximation
of such rational function operators on the whole real axis are
studied.
Keywords:rational function operators, Poisson integrals, convergence rate, uniform approximation, mean approximation Categories:41A20, 41A25, 41A35 

3. CMB 2016 (vol 60 pp. 300)
 Gauthier, Paul M; Sharifi, Fatemeh

Luzintype Holomorphic Approximation on Closed Subsets of Open Riemann Surfaces
It is known that if $E$ is a closed subset of an open Riemann
surface $R$ and $f$ is a holomorphic function on a neighbourhood
of $E,$ then it is ``usually" not possible to approximate $f$
uniformly by functions holomorphic on all of $R.$ We show, however,
that for every open Riemann surface $R$ and every closed subset
$E\subset R,$ there is closed subset $F\subset E,$ which approximates
$E$ extremely well, such that every function holomorphic on $F$
can be approximated much better than uniformly by functions holomorphic
on $R$.
Keywords:Carleman approximation, tangential approximation, Myrberg surface Categories:30E15, 30F99 

4. CMB 2016 (vol 59 pp. 760)
 Fichou, Goulwen; Quarez, Ronan; Shiota, Masahiro

Artin Approximation Compatible with a Change of Variables
We propose a version of the classical Artin
approximation
which allows to perturb the variables of the approximated solution. Namely, it is possible to approximate a formal solution of a
Nash equation by a Nash solution in a
compatible way with a given Nash change of variables.
This result is closely related to the socalled nested Artin
approximation and becomes false in the analytic setting. We provide
local and global versions of this approximation in real and complex
geometry together with an application to the RightLeft equivalence
of Nash maps.
Keywords:Artin approximation, global case, Nash functions Categories:14P20, 58A07 

5. CMB 2016 (vol 59 pp. 542)
 Jiang, Yongxin; Wang, Wei; Feng, Zhaosheng

Spatial Homogenization of Stochastic Wave Equation with Large Interaction
A dynamical approximation of a stochastic wave
equation with large interaction is derived.
A random invariant manifold is discussed. By a key linear transformation,
the random invariant manifold is shown to be close to the random
invariant manifold
of a secondorder stochastic ordinary differential equation.
Keywords:stochastic wave equation, homogeneous system, approximation, random invariant manifold, Neumann boundary condition Categories:60F10, 60H15, 35Q55 

6. CMB 2013 (vol 56 pp. 673)
 Ayadi, K.; Hbaib, M.; Mahjoub, F.

Diophantine Approximation for Certain Algebraic Formal Power Series in Positive Characteristic
In this paper, we study rational approximations for certain algebraic power series over a finite field.
We obtain results for irrational elements of strictly positive degree
satisfying an equation of the type
\begin{equation}
\alpha=\displaystyle\frac{A\alpha^{q}+B}{C\alpha^{q}}
\end{equation}
where $(A, B, C)\in
(\mathbb{F}_{q}[X])^{2}\times\mathbb{F}_{q}^{\star}[X]$.
In particular,
we will give, under some conditions on the polynomials $A$, $B$
and $C$, well approximated elements satisfying this equation.
Keywords:diophantine approximation, formal power series, continued fraction Categories:11J61, 11J70 

7. CMB 2011 (vol 56 pp. 337)
8. CMB 2011 (vol 55 pp. 752)
9. CMB 2011 (vol 55 pp. 762)
 Li, Hanfeng

Smooth Approximation of Lipschitz Projections
We show that any Lipschitz projectionvalued function
$p$ on a connected closed Riemannian manifold
can be approximated uniformly by smooth
projectionvalued functions $q$ with Lipschitz constant
close to that of $p$.
This answers a question of Rieffel.
Keywords:approximation, Lipschitz constant, projection Category:19K14 

10. CMB 2011 (vol 54 pp. 566)
 Zhou, XiangJun; Shi, Lei; Zhou, DingXuan

Nonuniform Randomized Sampling for Multivariate Approximation by High Order Parzen Windows
We consider approximation of multivariate functions in Sobolev
spaces by high order Parzen windows in a nonuniform sampling
setting. Sampling points are neither i.i.d. nor regular, but are
noised from regular grids by nonuniform shifts of a probability
density function. Sample function values at sampling points are
drawn according to probability measures with expected values being
values of the approximated function. The approximation orders are
estimated by means of regularity of the approximated function, the
density function, and the order of the Parzen windows, under
suitable choices of the scaling parameter.
Keywords:multivariate approximation, Sobolev spaces, nonuniform randomized sampling, high order Parzen windows, convergence rates Categories:68T05, 62J02 

11. CMB 2010 (vol 53 pp. 614)
 Böröczky, Károly J.; Schneider, Rolf

The Mean Width of Circumscribed Random Polytopes
For a given convex body $K$ in ${\mathbb R}^d$, a random polytope
$K^{(n)}$ is defined (essentially) as the intersection of $n$
independent closed halfspaces containing $K$ and having an isotropic
and (in a specified sense) uniform distribution. We prove upper and
lower bounds of optimal orders for the difference of the mean widths
of $K^{(n)}$ and $K$ as $n$ tends to infinity. For a simplicial
polytope $P$, a precise asymptotic formula for the difference of the
mean widths of $P^{(n)}$ and $P$ is obtained.
Keywords:random polytope, mean width, approximation Categories:52A22, 60D05, 52A27 

12. CMB 2009 (vol 53 pp. 11)
 Burke, Maxim R.

Approximation and Interpolation by Entire Functions of Several Variables
Let $f\colon \mathbb R^n\to \mathbb R$ be $C^\infty$ and let $h\colon
\mathbb R^n\to\mathbb R$ be positive
and continuous. For any unbounded nondecreasing sequence $\{c_k\}$
of nonnegative real numbers and for any sequence without
accumulation points $\{x_m\}$ in $\mathbb R^n$, there exists an entire
function $g\colon\mathbb C^n\to\mathbb C$ taking real values on $\mathbb R^n$ such that
\begin{align*}
&g^{(\alpha)}(x)f^{(\alpha)}(x)\lt h(x), \quad x\ge c_k, \alpha\le k,
k=0,1,2,\dots,
\\
&g^{(\alpha)}(x_m)=f^{(\alpha)}(x_m), \quad x_m\ge c_k, \alpha\le k,
m,k=0,1,2,\dots.
\end{align*}
This is a version for functions of several variables of the
case $n=1$ due to L. Hoischen.
Keywords:entire function, complex approximation, interpolation, several complex variables Category:32A15 

13. CMB 2009 (vol 52 pp. 28)
14. CMB 2008 (vol 51 pp. 372)
15. CMB 2007 (vol 50 pp. 434)
 Õzarslan, M. Ali; Duman, Oktay

MKZ Type Operators Providing a Better Estimation on $[1/2,1)$
In the present paper, we introduce a modification of the MeyerK\"{o}nig and
Zeller (MKZ) operators which preserve the test functions $f_{0}(x)=1$ and
$f_{2}(x)=x^{2}$, and we show that this modification provides a better estimation
than the classical MKZ operators on the interval $[\frac{1}{2},1)$ with
respect to the modulus of continuity and the Lipschitz class functionals.
Furthermore, we present the $r$th order generalization of our operators and
study their approximation properties.
Keywords:MeyerKÃ¶nig and Zeller operators, Korovkin type approximation theorem, modulus of continuity, Lipschitz class functionals Categories:41A25, 41A36 

16. CMB 2006 (vol 49 pp. 237)
17. CMB 2002 (vol 45 pp. 80)