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\author{D. H. Kim}
\title{Best polynomial approximation in Sobolev-Laguerre space}
\date{}
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\begin{abstract}
{\small %Small fonts for abstract
We discuss properties of best polynomial approximation for functions in }$%
\mathbf{W}^{N,2}[0,\infty ;e^{-x}]$ {\small for Sobolev inner product
\[
\phi (f,g):=\sum_{k=0}^{N-1}\int_{0}^{\infty
}f^{(k)}(x)g^{(k)}(x)e^{-x}dx+\gamma \int_{0}^{\infty
}f^{(N)}(x)g^{(N)}(x)e^{-x}dx,
\]
where $\gamma >0$ and $N\geq 1$ is a positive integer. } \vskip0.25cm {%
\noindent {\small \textsc{1991 ams subject classification : 33C45.}}} {%
\newline
\noindent {\small \textsc{key words : orthogonal polynomials.}}}
\end{abstract}

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