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JOURNALS // Matematicheskie Zametki // Archive

Mat. Zametki, 1995 Volume 58, Issue 2, Pages 163–175 (Mi mzm2034)

This article is cited in 1 paper

Existence of best approximation elements in $C(Q,X)$

L. P. Vlasov

Institute of Mathematics and Mechanics, Ural Branch of the Russian Academy of Sciences

Abstract: Generalizing the result of A. L. Garkavi (the case $X=\mathbb R$) and his own previous result concerning $X=\mathbb C$), the author characterizes the existence subspaces of finite codimension in the space $C(Q,X)$ of continuous functions on a bicompact space $Q$ with values in a Banach space $X$, under some assumptions concerning $X$. Under the same assumptions, it is proved that in the space of uniform limits of simple functions, each subspace of the form
$$ \biggl\{g\in B:\int_Q\bigl\langle g(t),d\mu_i\bigr\rangle=0,\ i=1,\dots,n\biggr\}, $$
where $\mu_i\in C(Q,X)^*$ are vector measures of regular bounded variation, is an existence subspace (the integral is understood in the sense of Gavurin).

Received: 04.04.1994


 English version:
Mathematical Notes, 1995, 58:2, 785–793

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