User zxmkn - MathOverflow Meta

zxmkn

Member for 7 years, 10 months
Last seen more than 2 years ago

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Stumbling around this world of math. Pease excuse my blunders.

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Jan 8, 2019

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13

Is $f^{-1}\big( \sqrt{xf(x)} \big)$ convex (for large $x$) when $f(x) = o(x)$ is concave and strictly increasing?

9

How is it "easily checked" that $[1-s(\cos\theta + i \sin \theta)] \sum_{n=0}^\infty s^n [\cos(n\theta)+i \sin(n\theta)] = 1$

9

Limit of matrix inverse: $\lim_{\lambda \to \infty} (A + \lambda I)^{-1} = \mathbf{0}$?

9

Problem solvable $\Rightarrow$ subproblems solvable if feasible region closed, convex?

8

Example of norm on $\mathbb{R}^2$ that's NOT absolutely monotonic.