“…Topological asymptotic expansions of the form (1) have been derived for many different problems constrained by linear PDEs. We refer the interested reader to [14,16,18,30,5,4,10,11,12] as well as the monograph [32]. Besides the field of shape and topology optimization, topological derivatives are also used in applications from mathematical imaging, such as image segmentation [25] or electric impedance tomography [26,28], or other geometric inverse problems such as the detection of obstacles, of cracks or of impurities of a material, see e.g., [16,23] and the references therein.…”