Proof.
Let be chosen with to be chosen later. Note that by Lemma 8.5,
for each there exists such that .
Consider the covering of , and choose an efficient
subcovering ,
where and the balls in are disjoint. The usual doubling arguments imply
that .
By Theorem 8.3, if we are given , then we can choose such that
for each we have , while for each
we have .
Let be the group associated to , and for each let be
the largest integer such that . Let with
the corresponding point. Note that for sufficiently small, we have
, and in particular, for every
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(8.50) |
Consider the collection of balls . Clearly, by construction, conditions (1) and (3) are satisfied.
If then since cover we have that for some that
, which implies , as claimed.
∎