diff --git a/tutorials/what-are-manifolds.qmd b/tutorials/what-are-manifolds.qmd index 0e045349..f76f56fe 100644 --- a/tutorials/what-are-manifolds.qmd +++ b/tutorials/what-are-manifolds.qmd @@ -158,14 +158,15 @@ I(\gamma) = \int_a^b F(\gamma(t), \dot{\gamma}(t)) dt where $F \colon T\mathcal{M} \to [0, \infty)$ is a certain scalar function on tangent bundle called Finsler metric.[BaoChernShen:2000](@cite) It has the following properties: -* The function $F$ is smooth on $TM \setminus \{0\}$. +* The function $F$ is smooth on $T \mathcal{M} \setminus \{0\}$. * For all $p\in \mathcal{M}$, $X \in T_p \mathcal{M}$ and $\lambda \geq 0$ the metric is homogeneous: $F(p, \lambda X) = \lambda F(p, X)$. * Strong convexity: at each $p\in \mathcal{M}$ the Hessian of $X \mapsto \frac{1}{2}F^2(p, X)$ is positive definite[^no-strong-convexity]. This Hessian $g_{p}$ is called the fundamental tensor. For each point $p$ the function $X \mapsto F(p, X)$ is a Minkowski norm on $T_p\mathcal{M}$, that is the following properties hold: * Positivity: $F(p, X) > 0$ for all $X \neq 0$, * Triangle inequality: $F(p, X_1 + X_2) \leq F(p, X_1) + F(p, X_2)$, -* Fundmental inequality: $g_p(X_1, X_2) \leq F(p, X_1)F(p, X_2)$.[^fundamental-inequality] +* Fundamental inequality: $g_p(X_1, X_2) \leq F(p, X_1)F(p, X_2)$.[^fundamental-inequality] + The Finsler metric can be calculated using [`norm`](@ref). Despite a very generic description, Finsler manifolds provide a rich structure.