# Phase Flow

$g^t:({\bf{p}}(0),{\bf{q}}(0))\longmapsto({\bf{p}}( t),{\bf{q}}(t))$,
where ${\bf{p}}(t)$ and ${\bf{q}}(t)$ are solutions of the Hamilton's system of equations corresponding to initial condition ${\bf{p}}(0)$and ${\bf{q}}(0)$.
Show that $\{g^t\}$ is a group.