  Quasi-set theory provides a mathematical background for dealing with
collections of indistinguishable elementary particles. In this paper, we show
how to obtain the quantum statistics into the scope of quasi-set theory and
discuss the Helium atom, which represents the simplest example where
indistinguishability plays an important role. A brief discussion about
indistinguishability and interference is also presented as well as other
related lines of work. One of the advantages of our approach is that one of the
most basic principles of quantum theory, namely, the Indistinguishability
Postulate, does not need to be assumed even implicetely in the axiomatic basis
of quantum mechanics.
