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On any given compact manifold Mn+1 with boundary ∂M, it is proved that the
moduli space E of Einstein metrics on M, if non-empty, is a smooth, infinite
dimensional Banach manifold, at least when π1(M,∂M) = 0. Thus, the
Einstein moduli space is unobstructed. The usual Dirichlet and Neumann
boundary maps to data on ∂M are smooth, but not Fredholm. Instead, one has
natural mixed boundary-value problems which give Fredholm boundary
maps.
These results also hold for manifolds with compact boundary which have a finite
number of locally asymptotically flat ends, as well as for the Einstein equations
coupled to many other fields.
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