| Abstract: | Some criteria are proved for an element of a Banach space to belong to the test or Korovkin closure of a given set. The operations
of closure in question are determined by linear functionals. The cases of arbitrary linear functionals and of positive functionals
are considered. Some sufficient conditions are given for the test closure to coincide with the Korovkin closure. Bibliography:
33 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 247, 1997, pp. 114–145.
Translated by S. Yu. Pilyugin. |
