  The paper is devoted to the study of quasi-static brittle crack evolution. We
work under the following assumptions: a linear elastic body, with or without
initial cracks inside, evolves in a quasi-static manner under an imposed path
of boundary displacements. During its evolution cracks with unprescribed
geometry may appear and/or grow.
  This is an alternative version of the published article [Bu3], containing an
improved Mumford-Shah model based on the functional K2, a generalization of the
integral J of Rice. Further information at
http://irmi.epfl.ch/cag/buliga_bfrac.html or http://www.imar.ro/~marius/ .
