Presented here is a discussion on the connection between geometric qua
ntization and algebraic quantization. The former procedure relies on a
construction of unitary irreducible representations that starts from
co-adjoint orbits and uses polarizations, while the latter depends on
the Purely algebraic characterization of unitary irreducible represent
ations, which is based on central decompositions of von Neumann algebr
as in involutive duality, and their decompositions in terms of maximal
Abelian subalgebras. Intermediate stages of these two quantization me
thods turn out to be complementary, leading thus to a new characteriza
tion of the so-called discrete series representations. (C) 1994 Americ
an Institute of Physics.