1. Method for the construction, within a computer system, of at least one model of a complex electronic system including a plurality of constituents, each system model including a hierarchised set of modelled constituents, said construction method comprising, for each model: obtaining a multiple instance hierarchical model including at least one instance vector corresponding to a plurality of instances of one and the same modelled constituent, each instance vector being able to be located at any level of a hierarchical decomposition tree of said multiple instance hierarchical model: expanding said multiple instance hierarchical model into an expanded model, by expansion of at least one instance vector included in said multiple instance hierarchical model.