  The notion of state vector is, in quantum mechanics, as central as it is
problematic, as illustrates the wealth of publications about the sub- jects,
including in particular the many attempts to obtain an acceptable
interpretation of quantum mechanics. In this article, we propose a different
approach, and initiate the study of a formulation of quantum mechanics, where
the notion of state is entirely replaced by assertions about measurement
outcomes. We define a notion of "verification" which represents the knowledge
that one may have about the possible outcomes of the measurements performed on
a quantum system, and express a set of logical rules which allow to reason
about quantum systems using verification assertions only, and thus making no
reference to the problematic notion of state.
