New method for studying the microscopic foundations of the interacting boson model

We describe (i) a mapping, using a multishell seniority basis, from a prescribed subspace of a shell model space to an associated boson space. (ii) A new dynamical procedure for selecting the collective variables within the boson space, based on the invariance of the trace. (iii) A comparison with exact calculations for a multi-level pairing model, to demonstrate that the method works. (orig.)