Cook’s boundary condition
on the conformal factor
(Equation (82)
in [72
]) is equivalent
to
which (in
the co-rotating case, or more
generally, when the 2-metric on
is axi-symmetric) reduces to
on
. The Yo et al. boundary
condition on
(Equation (48)
of [190]) is equivalent
to
on
, where, however, the
evolution vector field
is obtained by a superposition
of two Kerr-Schild data.