We review in a pedagogical fashion the 3+1-split which serves to put
Einstein's equations into the form of a dynamical system with constraints. We
then discuss the constraint equations under the simplifying assumption of
time-symmetry. Multi-Black-Hole data are presented and more explicitly
described in the case of two holes. The effect of different topologies is
emphasized.Comment: 18 pages, Latex, uses Springer style-file lamuphys.sty. To appear in
"Black Holes: Theory and Observation", edited by F. Hehl, C. Kiefer and R.
Metzler, Springer 199
