Korovkin sets in Banach space for sets of linear functionals

Test closures of sets in Banach spaces generated by linear functionals

“…One can fbrmulate similar problems for Korovkin sets. Among numerous publications containing solutions of Problem 1 for various E, X, Y, F, and (I), we mention [2,[7][8][9][10][11][12][13][14][15][16][17] (for Korovkin sets) and [8,9,[18][19][20][21] (Ibr test sets). These papers contain explicit conditions for the case of functionals.…”