Dini's Theorem states: Let $[a,b]$ be a compact intervall. Let $f,f_{n}: [a,b] \xrightarrow{} \mathbb{R}$, $ n \in \mathbb{N}$, functions with
- $f$ and $f_{n}$ are continuos for all $n$
- $\lim_\limits{n \to \infty} f_{n}(x) = f(x)$ $\forall x \in [a,b]$
- $f_{n}(x) \leq f_{n+1}(x)$ $\forall x \in [a,b]$ and $n \in \mathbb{N}$.
Then $\{f_{n}\}_{n \in \mathbb{N}}$ converges uniformly to $f$.
Suppose only conditions $1$ and $2$ are satisfied. Are in this case $\{f_{n}\}_{n \in \mathbb{N}}$ also converges uniformly to $f$?
The reason why I'm asking this quesion ist that I found a variant of Dini's theorem that states if condition $1$ and $2$ are satisfied and we have that $f_{n}$ is a so called commute sequence, i.e. f_{n} has a monotonically increasing and a monotonically decreasing part, then Dini's Theorem also holds
Let $f_n(x)=nx$ for $x \in [0,\frac 1 n]$ and $f_n(x)=2-nx$ for $x \in [\frac 1 n, \frac 2 n]$, $0$ in the rest of $[0,1]$. Then $f_n \to 0$ pointwise but not uniformly since $f_n(\frac 1 n) =1$ for all $n$.