  An important problem when modeling gene networks lies in the identification
of parameters, even if we consider a purely discrete framework as the one of
Ren\'e Thomas. Here we are interested in the exhaustive search of all parameter
values that are consistent with observed behaviors of the gene network. We
present in this article a new approach based on Hoare Logic and on a weakest
precondition calculus to generate constraints on possible parameter values.
Observed behaviors play the role of "programs" for the classical Hoare logic,
and computed weakest preconditions represent the sets of all compatible
parameterizations expressed as constraints on parameters. Finally we give a
proof of correctness of our Hoare logic for gene networks as well as a proof of
completeness based on the computation of the weakest precondition.
