  Shrinkage of large particles, either through depolymerisation (i.e.
progressive shortening) or through fragmentation (breakage into smaller pieces)
may be modelled by discrete equations, of Becker-D\''oring type, or by
continuous ones. In this note, we review two kinds of inverse problems: the
first is the estimation of the initial size-distribution from moments
measurements in a depolymerising system, in collaboration with Philippe Moireau
and inspired by experiments carried out by Human Rezaei's team; the second is
the inference of fragmentation characteristics from size distribution samples,
in collaboration with Miguel Escobedo and Magali Tournus, based on biological
questions and experiments of Wei-Feng Xue's team.
