New posts in Counterexamples

Why $M_1 \subset M_2 \not \Rightarrow N_{M_1} (\lambda) \leq N_{M_2} (\lambda)$ for eigenvalue problem? (EDIT)

Spaces for which separable is equivalent to second-countable

ODE properties true in finite dimension but not in Banach spaces of infinite dimension

Can a subset of the plane have nontrivial $H_2$ or $\pi_2$?

Results true in a dimension and false for higher dimensions

Conjecture of Spira on the zeros of $\zeta^\prime(s)$

Counterexamples to differentiation under integral sign?

Example of a manifold which is not a homogeneous space of any Lie group

Convergence of finite element method: counterexamples

Haar measure for large locally compact groups