0040現代数学の系譜 雑談 古典ガロア理論も読む ◆e.a0E5TtKE
2017/12/28(木) 23:41:49.82ID:IsA0R4yK沢山のレスがありがとう
まあ、ゆっくりやろう
まだ、疑問に思っているのは
下記のDifferentiability of the Ruler Functionの記述と貴方の定理との整合性だ
http://mathforum.org/kb/message.jspa?messageID=5432910 (>>35より)
Topic: Differentiability of the Ruler Function Dave L. Renfro Posted: Dec 13, 2006 Replies: 3 Last Post: Jan 10, 2007
(抜粋)
The ruler function f is defined by f(x) = 0 if x is
irrational, f(0) = 1, and f(x) = 1/q if x = p/q
where p and q are relatively prime integers with q > 0.
Using ruler-like functions that "damp-out" quicker
than any power of f gives behavior that one would
expect from the above.
Let w:Z+ --> Z+ be an increasing function that
eventually majorizes every power function. Define
f_w(x) = 0 for x irrational, f_w(0) = 1, and
f_w(p/q) = 1/w(q) where p and q are relatively
prime integers.
** f_w is differentiable on a set whose complement
has Hausdorff dimension zero. Jurek [4] (pp. 24-25)
Interesting, each of the sets of points where these
functions fail to be differentiable is large in the
sense of Baire category.
THEOREM: Let g be continuous and discontinuous on sets
of points that are each dense in the reals.
Then g fails to have a derivative on a
co-meager (residual) set of points. In fact,
g fails to satisfy a pointwise Lipschitz
condition, a pointwise Holder condition,
or even any specified pointwise modulus of
continuity condition on a co-meager set.
(Each co-meager set has c points in every interval.)
つづく