I'm trying to learn math on my own. The bad thing is, I can't google latex letters and they often have multiple meanings. For exmaple ${\mathcal{L}}$ could stand for lagrangian or something else.
The question: What means in the following (nameless) theorem ${\mathcal{L}}$?
Theorem:
Let $U \subset \mathbb{R}^n$ be open and $f \in \mathcal{C}^1(U,\mathbb{R}^n)$. Let also be $\tilde x \in U$ and $\delta >0$, $q \in (0,1)$ with following properties:
$ L := df(\tilde x) \in {\mathcal{L}(\mathbb{R}^n)}$ can be inverted with Inversion $L^{-1} \in {\mathcal{L}(\mathbb{R}^n)}$
...
Background: Implicit function theorem is followed by this.
Usually $\mathcal{L}(V)$ is the space of linear maps from $V$ to itself. I'd be surprised if this notation wasn't explained somewhere earlier in the book this is from.