- PROOF OF THE STABILITY OF HYPERBOLIC LIMITS 229
To see (33.26), first note that by (33.24) we have
(33.28)
for all i. Moreover, for i large enough
(33.29)
by (33.22) and since qii : (fh h) ---+ (Vi, g (f3i)lv) is as close to an isometry as we
like in any Ck-norm.^10 Thus qi;^1 o Fi (f3i), as measured from h to h, is close to an
isometry in its domain.
Since HA is compact, it follows from (33.28) and (33.29) for our given k, that
qi;^1 o Fi (f3i) (HA) c B (:i\'°, C)
for some C < oo independent of i. Since the sequence {U°diEN exhausts il, we have
that for i large enough, qi;^1 o Fi (f3i) (HA) C Ui C il; that is,
Fi (,Bi) (HA) c Vi c M,
which is (33.26). Since Fi (f3i)-^1 (Vi) =HA, we have that (33.29) says
(33.30) II (qi;
1
o Fi(f3i))* h - hl1iA llck(HA,h) :S ~-
Now consider the embeddings
<I.>:--^1 oF; (/3;) - -
H A ' ui c H
F;(/3; ) \. ,/<I!;
M.
By (33.30) and the "Arzela- Ascoli theorem for maps" (see Claim 2 in the proof of
Proposition 33.14), we have that { qi;^1 o Fi (f3i)} subconverges in ck-^1 (HA, h) to
a map W 00 : HA---+ il.
Moreover, by (33.22) we have
(33.31)
Now qi; g (f3i) converges to h in C^00 on compact sets, while we only know that
qi;^1 o Fi (,Bi) converges to W 00 in Ck-^1 (HA, h). However, we claim that by passing
to a subsequence, the latter convergence is also in C^00 (HA)· Because of this, we
(^10) Note that (Fi (,Bi)-^1 r his close tog (,Bi)·