In this paper we investigate weighted polynomial approximations with several
variables. Our study relates to the approximation for by weighted
polynomial. Then we will give some results relating to the Lagrange interpolation,
the best approximation, the Markov-Bernstein inequality and the Nikolskii-
type inequality.

Jung, H.S. and Sakai, R. (2009) Specific Examples of Exponential Weights. Communications of the Korean Mathematical Society, 24, 303-319.
https://doi.org/10.4134/CKMS.2009.24.2.303

Sakai, R. and Suzuki, N. (2013) Mollification of Exponential Weights and Its Application to the Markov-Bernstein Inequality. The Pioneer Journal of Mathematics, 7, 83-101.

Jung, H.S. and Sakai, R. (2016) Lp-Convergence of Lagrange Interpolation Polynomials with Regular Symmetric Exponential Type Weight. Global Journal of Pure and Applied Mathematics, 12, 797-822.