van abel

326 reputation

bio	website	wamath.sinaapp.com
	location	china
	age	25
visits	member for	1 year, 6 months
	seen	yesterday
stats	profile views	50

I am a postgraduate student in Southwest University, Chongqing, China, majored in elementary mathematics and interested fields include Riemannian Geometry and Elliptic Differential Equation. I always confused about the textbooks, so I would like have a discussion with anybody on the net.

	326 reputation	bio	website	wamath.sinaapp.com	visits	member for	1 year, 6 months
18 badges		location	china		seen	yesterday

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1d	asked	Does there exist a smooth function which is nowhere analytic?
May 14	awarded	Caucus
May 6	awarded	Yearling
May 5	accepted	Is this a dominated convergence theorem?
May 4	comment	Is this a dominated convergence theorem? That's great!, how about require $U$ be bounded?
May 4	asked	Is this a dominated convergence theorem?
May 4	accepted	Did there exists a counterexample says that the Dominated convergence Theorem must has a control function rather than the limits function?
May 1	asked	Did there exists a counterexample says that the Dominated convergence Theorem must has a control function rather than the limits function?
Apr 20	asked	How to show a basic integral inequality?
Apr 16	comment	Is there an exact example which show that the non-negativity in weak maximum principle is necessary? It's nothing wrong with the statement, since in you example, $u^+\equiv0$, hence $u^+$ attains its maximum in $\Omega$ at the boundary!
Apr 15	answered	How to show that a measurable function on $R^d$ can be approximated by step functions?
Apr 15	comment	Approximation of a bounded measurable function with step functions? Did the proposition also hold in the case that $f$ is measurable on $R^1$ rather than the bounded set $[0,1]$? see also:math.stackexchange.com/questions/361233/…
Apr 15	revised	How to show that a measurable function on $R^d$ can be approximated by step functions? edited title
Apr 15	comment	How to show that a measurable function on $R^d$ can be approximated by step functions? See also:math.stackexchange.com/questions/362406/…
Apr 15	asked	Can a measurable function in $R^d$ be approximated by step function?
Apr 15	revised	Is there an exact example which show that the non-negativity in weak maximum principle is necessary? delete "only" since which will make the question sounds like Strong MP
Apr 15	comment	Is there an exact example which show that the non-negativity in weak maximum principle is necessary? Yes, you were right. I need to correct it!
Apr 14	comment	How to show that a measurable function on $R^d$ can be approximated by step functions? Since the convergence may depended on $x$, thus you can't taken an subsequence of step function for "every x".
Apr 14	comment	How to show that a measurable function on $R^d$ can be approximated by step functions? It sames that the argument must depended on Egonov's Theorem, but how to, I don't know.
Apr 14	asked	How to show that a measurable function on $R^d$ can be approximated by step functions?