In this paper we extend recent work on the detection of inclusions
using electrostatic measurements to the problem of crack detection
in a two-dimensional object. As in the inclusion case our method is
based on a factorization of the difference between two
Neumann-Dirichlet operators. The factorization possible in the case
of cracks is much simpler than that for inclusions and the analysis
is greatly simplified. However, the directional information carried
by the crack makes the practical implementation of our algorithm
more computationally demanding.