188
DOC.
13
GENERALIZED THEORY OF RELATIVITY
Since
i
is
interchangeable
with
k,
and
u
with
v,
we can
write the second
sum
as
aßfxv ik
VXa ÖXa
OX
=
-2.
«fe
V
a*"
aß
a*
MV
a*.
a*,
Hence,
the
identity sought
reads
2U
-
V
+
W
+
2X
=
2A
-
B,
and is thus
identical with the
one given
in Part
I, §5.