Extension of bounded linear functionals and best approximation in spaces with asymmetric norm

The present paper is concerned with the characterization of the elements of best approximation in a subspace $Y$ of a space with asymmetric norm, in terms of some linear functionals vanishing on $Y$. The approach is based on some extension results, proved in Section 3, for bounded linear functionals on such spaces. Also, the well known formula for the distance to a hyperplane in a normed space is extended to the nonsymmetric case

The approximation by spline functions of the solution of a singularly perturbed bilocal problem

Not available