Lens reconstruction and source redshift distribution
  The currently used linear and nonlinear lens inversion techniques are based on distortion estimators whose complicated source redshift dependence makes the influence of the redshift distribution of the sources difficult to take into account and to analyze. However, the lens equations can be explicitly averaged over the source redshift distribution by a suitable choice of the estimators. Lens reconstruction procedures are outlined, which make use of all the information and in which all the unknown quantities of the problem can be recovered simultaneously in both the linear and nonlinear regime, for either noncritical or critical lenses. These procedures require no prior knowledge of the redshift distribution of the sources, but are possibly dependent on the Cosmology in some instances. Possible methods of recovery of the source redshift distribution itself are briefly discussed at the same time. 
Pierre-Yves Longaretti (Observatoire de Grenoble, France)