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### Questions (18)

 11 A Problem in Evans' PDE 9 A harmonic function which is bounded by $\ln(|x|)$ at infinity 7 Is $C_c^{\infty}$ dense in $X_0^{\alpha}$? 7 Do the two limits coincide? 6 An inequality of J. Necas

### Reputation (494)

 +35 A Problem in Evans' PDE +5 Is there an elliptic regularity for the whole space? +5 An inequality of J. Necas +5 Linear Fractional Transforms maps the upper half unit disc onto the first quadrant

 8 Prove the inequality $a^2bc+b^2cd+c^2da+d^2ab \leq 4$ with $a+b+c+d=4$ 7 Find all continuous functions $f:\mathbb{R}\to\mathbb{R}$, that satisfy $f(xy)=f(\frac{x^2+y^2}{2})+(x-y)^2$ 3 Find a side of a triangle given other two sides and an angle 1 how to solve these questions with congruences 0 Continuous piecewise smooth function $=$ a globally $\mathcal{C}^1$ function $+\sum a_i|s-\alpha_i|$?

### Tags (14)

 8 inequality × 6 0 real-analysis × 10 7 functional-equations 0 sobolev-spaces × 5 3 trigonometry 0 functional-analysis × 2 1 elementary-number-theory 0 measure-theory × 2 0 pde × 11 0 holder-spaces

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