New posts in Examples Counterexamples

Must continuous $H^1(\mathbb{R}^2)$ function tend to zero at infinity?

$T_1$ spaces where the closure of a compact set is not compact

Is the derivative always nonnegative in a neighbourhood of a minimum?

Can monics always be "made left-invertible" by adding arrows?

Various examples of non-representable functors

Must the set of explosion points be countable?

Prove $\sqrt[3]{\frac{(a^4+b^4)(a^4+c^4)(b^4+c^4)}{abc}}\ge \sqrt{\frac{(a^3+bc)(b^3+ca)(c^3+ab)}{1+abc}}$

Example of function such that its each derivative and itself vanishes at 0 but any polynomial multiple of that function doesnot vanishes at infinity

Find a counterexample: For every antiprime $n>1$, there is a prime divisor $p$ such that $n/p$ is an antiprime

Simple Failings of Axiom of Choice in Top