A counterexample concerning the L_2-projector onto linear spline spaces

Peter Oswald

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A counterexample concerning the L_2-projector onto linear spline spaces

Peter Oswald

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Abstract

For the L_2-orthogonal projector P onto spaces of linear splines over simplicial partitions of polyhedral domains in R^d, d>1, we show that the L_infty norm of P cannot be bounded uniformly with respect to the partition. This is in contrast to d=1, where these norms are bounded by 3 independently of the partition. This negative result is folklore among specialists in finite element methods and approximation theory but seemingly has never been formally proved.

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Peter Oswald. 2006-11-19. A counterexample concerning the L_2-projector onto linear spline spaces. https://arxiv.org/abs/math/0611573

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