New posts in Functional Analysis

Compactness in normed vector spaces.

Find function $f(x)$ satisfying $\int_{0}^{\infty} \frac{f(x)}{1+e^{nx}}dx=0$

Is there a version of the Arzelà–Ascoli theorem capturing $C([0,\infty))$?

A proof for $\nabla |u|^p = p\ \text{sgn}(u)|u|^{p-1}\nabla u$.

Is the space of piecewise continuous functions on $[0,1]$ complete in $L^2[0,1]$?

Are polynomials dense is L2 of the unit disk?

Weak solutions to $\Delta u=f$ are in $W^{2,2}$

Extending the spectral theorem for bounded self adjoint operators to bounded normal operators

Non-Borel set in arbitrary metric space

$\Delta u=3u$ then $u\equiv0$