I will I review the 3+1-decomposition of GR or other field theories done in such a way that the time leaves need not form a foliation, i.e. where the lapse function can become zero or even change sign. I make remarks on local existence as well as on the relation with the 'hypersurface deformation algebra' put forward by Teitelboim, Kuchar and others.
Robert Beig (Vienna): The ADM decomposition 'done right'
