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スレ47 ｽﾚﾘﾝｸ(math板:245番)
245 現代数学の系譜 雑談 古典ガロア理論も読む ◆e.a0E5TtKE [sage] 投稿日：2017/12/02
ちょっと、ピエロの過去レス46に戻る
スレ46 ｽﾚﾘﾝｸ(math板:181番)
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181 返信：１３２人目の素数さん[sage] 投稿日：2017/11/15(水) 19:42:29.78 ID:fz0TcIh0 [2/3]
(抜粋)
さらにいえば、1/q^nを1/e^(-q)に置き換えても
リュービル数では微分不可能URLﾘﾝｸ(kbeanland.files.wordpress.com)
(引用終り)
これ、結構面白ね（＾＾
要するに、Proposition 3.1で、無理数で０で有理数でプラス（T(x)＞０ xは有理数）となるどんな関数も、必ずどこか微分不可能な無理数があり、それは稠密だというのだ（下記PDF）
URLﾘﾝｸ(kbeanland.wordpress.com)
Kevin Beanland ASSOCIATE PROFESSOR OF MATHEMATICS in the Department of Mathematics at Washington and Lee University.
Research Articles
My main research area is Banach space theory but, I have some work in real analysis and know some descriptive set theory as it applies to Banach space theory.
URLﾘﾝｸ(kbeanland.files.wordpress.com)
Modifications of Thomae’s function and differentiability, (with James Roberts and Craig Stevenson) Amer. Math. Monthly, 116 (2009), no. 6, 531-535.
(抜粋)
3. A DENSE SET. While attempting to prove that T(1/n2) is differentiable on the irrationals,
we discovered that quite the opposite is actually true. In fact, as the following
proposition indicates, functions that are zero on the irrationals and positive on the rationals
will always be non-differentiable on a rather large set.
Proposition 3.1. Let f be a function on R that is positive on the rationals and 0 on
the irrationals. Then there is an uncountable dense set of irrationals on which f is not
differentiable.
(引用終り)