Throughout,
M
will denote a
C
compact connected oriented
n
-manifold,
n
2
. Let
: M

be a
C
function,

the space of
C
riemannian metrics on
M
and
where
R(g)
is the scalar curvature of
g
. A superscript
s
will denote objects in the corresponding Sobolev space,
s >
n + 1
(one can also treat
Ws, p
spaces in the same way), and we also allow
s = 
so

= 
.