Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 36 No. 2 2011 01 03 Chebyshev Centers and Approximation in Pre-Hilbert C*-Modules209 216 en A. Niknam Ferdowsi University of Mashhad S. Shadkam Ferdowsi University of Mashhad 2011 01 03 Farthest point chebyshev center uniquely remotal set Hilbert C*-module Avalued norm