  This paper continues the study of infinite dimensional bicomplex Hilbert
spaces introduced in previous articles on the topic. Besides obtaining a Best
Approximation Theorem, the main purpose of this paper is to obtain a bicomplex
analogue of the Riesz-Fischer Theorem. There are many statements of the
Riesz-Fischer (R-F) Theorem in the literature, some are equivalent, some are
consequences of the original versions. The one referred to in this paper is the
R-F Theorem which establishes that the spaces $l^2$ is the canonical model
space.
