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An expert is a man who has made all the mistakes, which can be made, in a very narrow field. (Niels Bohr)


Jul
24
asked Banach Fixed Point Theorem. Measurable version.
Jul
10
asked $ d(x,y)^2 \le d(x,z)^2 - d(y,z)^2\color{}{+\varphi\big(x,y,z,d(x,y),d(y,z) \big)}? $
Apr
27
answered If $f$ is uniformly continuous on $\mathbb{R}$, $f(x) \ge a >0$ and $g(x) = 1/f(x)^2$, then $g(x)$ is uniformly continuous
Apr
20
answered $XD = DX$ then $X$ is diagonal
Mar
29
answered Interchanging the limiting operations
Mar
2
answered How do i solve delta epsilon proofs for quadratic equations?
Mar
1
answered Continuous function?
Feb
12
answered If $f,g$ are uniform continuous with $f$ bounded, then $fg$ is uniform continuous.
Feb
7
asked Why 'closed differential forms' are called 'closed'?
Feb
7
answered Mathematical equivalent of Feynman's Lectures on Physics?
Jan
25
answered A Tricky Limit: $\lim \limits_{x\rightarrow 0} \frac{9^x-5^x}{x}$ without L'Hospital
Jan
14
answered Proof that $x^k < k^x$
Jan
7
asked Growth Rate. A precise definition.
Jan
2
answered Solution verification: solving $\sqrt{x-4}-\sqrt{x-5}+1=0$
Dec
30
answered If $f:\mathbb{R}\to\mathbb{R}$ is continuous and $f(x)\neq x$ for all $x$, must it be true that $f(f(x))\neq x$ for all $x$?
Dec
30
answered Taylor series for $e^z\sin(z)$
Dec
28
answered Differentiation of exponential function?
Dec
28
answered properties of positive definite matrix
Dec
24
asked The problem of the most visited point.
Nov
17
answered $|a_n - a_m| \le \sum_{k=m}^{n-1} |a_{k+1} - a_k|$