Let
(M,g) be a closed Riemannian
manifold of dimension
5≤n≤7.
Assume that
(M,g)
is not conformally equivalent to the round sphere. If the scalar curvature
Rg is greater than or equal
to 0 and the
Q-curvature
Qg is greater than
or equal to 0 on
M
with
Qg(p)>0 for
some point
p∈M,
we prove that the set of metrics in the conformal class of
g with prescribed constant
positive
Q-curvature
is compact in
C4,α
for any
0<α<1.
Keywords
compactness, constant Q-curvature metrics, blowup
argument, positive mass theorem, maximum principle, fourth
order elliptic equations