Kerr metric derivation (Adler, Bazin & Schiffer)

1. Jun 15, 2010

I have a problem understanding part of Adler, Bazin and Schiffer's (Introduction to General Relativity 2nd Edition) derivation of the Kerr metric. I would be grateful if someone could explain where I am going wrong. My problem concerns the transition from the O(m2) equation (7.15b) to (7.24). For the first term of (7.15b) I get:

m2.lm.ln[4(A.la)|a-8A2]

while for the second term (INCLUDING the minus sign preceding the 2 Minkowski metrics):

m2.lm.ln[-6A2-2.la|b.lb|a+2.la|b.la|b]

Adding these 2 expressions does not produce a factor of the LHS of (7.24), although subtracting them does.

2. Jun 16, 2010