  to turducken (turduckens, turduckening, turduckened, turduckened) [math.]: To
stuff a black hole. We analyze and apply an alternative to black hole excision
based on smoothing the interior of black holes with arbitrary - possibly
constraint violating - initial data, and solving the vacuum Einstein evolution
equations everywhere. By deriving the constraint propagation system for our
hyperbolic formulation of the BSSN evolution system we rigorously prove that
the constraints propagate causally and so any constraint violations introduced
inside the black holes cannot affect the exterior spacetime. (This does not
follow from the causal structure of the spacetime as is often assumed.) We
present numerical evolutions of Cook-Pfeiffer binary black hole initial
configurations showing that these techniques appear to work robustly for
generic data. We also present numerical evidence from spherically symmetric
evolutions that for the gauge conditions used the same stationary end-state is
approached irrespective of the choice of initial data and smoothing procedure.
