Definition:Variation of Admissible Curve

Definition
Let $M$ be a smooth manifold.

Let $I = \closedint a b$ be a closed real interval.

Let $\gamma : I\to M$ be an admissible curve.

Let $J \subseteq \R$ be an open real interval containing $0$.

Let $\Gamma : J \times I \to M$ be an admissible family of curves such that:


 * $\ds \forall t \in J : \forall s \in I : \tuple {s, t} \stackrel \Gamma \mapsto \map {\Gamma_s} t$

Suppose $\map {\Gamma_0} t = \map \gamma t$.

Then $\Gamma$ is called the variation of $\gamma$.