RIDGE FUNCTIONS;
GOOD SETS;
LINEAR SUPERPOSITIONS;
APPROXIMATION;
INTERPOLATION;
VARIABLES;
PRODUCT;
D O I:
10.1016/j.crma.2017.09.015
中图分类号:
O1 [数学];
学科分类号:
0701 ;
070101 ;
摘要:
We give a necessary condition for the representation of the space of continuous functions by sums of its k closed subalgebras. A sufficient condition for this representation problem was first obtained by Sternfeld in 1978. In case of two subalgebras (k = 2), our necessary condition turns out to be also sufficient. If k = 1, our result coincides with a version of the classical Stone-Weierstrass theorem. (C) 2017 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.