Title:       A nonstandard finite element interpolation estimate

Author:      Susanne C. Brenner

Published:   Numerical Functional Analysis and Optimization,
             v. 20 (1999), 245-250 (MR# 2000b:65210)

Abstract:    We show that $\|\uI\|_{H^\oep(\O)}\leq C\|u\|_\HeO$, where $\O$ 
             is a bounded polygonal domain in $\R^2$, $0<\epsilon<(1/2)$, 
             $\uI$ is the piecewise linear nodal interpolant of $u$ with 
             respect to a triangulation of $\O$, and $C$ depends only on    
             $\epsilon$ and the minimum angle of the triangulation.  
             Extensions to other finite element nodal interpolations are also 
             discussed.