# Qinfeng Li

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bio website location West Lafayette, IN age 25 member for 3 years, 7 months seen Dec 8 at 22:54 profile views 49

I'm interested in analysis and algebraic topology. Currently I'm reading something about geometric measure theory.

# 11 Questions

 8 How to prove such an elementary inequality 4 A problem about uniform convergence 3 Show the convergence of the integral $F(t,x)=\int_{-\infty}^{+\infty}\exp[i\tau t-(i\tau)^{1/2}x - (i\tau)^\theta] \,d\tau$ 3 Real analysis by E. M. Stein: Chapter 1,Problem 7 1 $H^{n-1} (spt \mu _E - \partial ^{*}E)=0 ?$

# 165 Reputation

 +5 $H^{n-1} (spt \mu _E - \partial ^{*}E)=0 ?$ +2 show that there exits a analytic cube root of a function on a domain +15 Show the convergence of the integral $F(t,x)=\int_{-\infty}^{+\infty}\exp[i\tau t-(i\tau)^{1/2}x - (i\tau)^\theta] \,d\tau$ +15 Show that for all $(\tau, \xi) \in \mathbb R^{n+1}$ we have $|(\tau-ia)^2 - |\xi|^2| \ge a(\tau ^2+|\xi|^2+a^2)^{1/2}$

# 5 Answers

 1 Uniqueness of Pexider's functional equation 0 Prove that $AA^T=0\implies A = 0$ 0 Show that for all $(\tau, \xi) \in \mathbb R^{n+1}$ we have $|(\tau-ia)^2 - |\xi|^2| \ge a(\tau ^2+|\xi|^2+a^2)^{1/2}$ 0 Conformal mapping vertical strip $\{-1 < Re(z) < 1\}$ onto open unit disk $D$ in $\mathbb{C}$. 0 Prove the open mapping theorem by using maximum modulus principle

# 18 Tags

 1 functional-equations 0 calculus 0 pde × 4 0 linear-algebra 0 complex-analysis × 4 0 measure-theory 0 real-analysis × 4 0 integral-inequality 0 inequality × 2 0 fourier-analysis

# 3 Accounts

 Mathematics 165 rep 10 MathOverflow 8 rep 4 TeX - LaTeX 1 rep

# 10 Badges

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# 41 Votes Cast

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41 up 14 question
0 down 27 answer