Characteristic line field
= Characteristic line field
{title2=$\ker(\omega|_{TN})$}
For a hypersurface $N$ of a <symplectic manifold>, the restriction of the <symplectic form> has a one-dimensional kernel, its characteristic line field. On a <regular value> level $N=H^{-1}(c)$, this line is generated by the <Hamiltonian vector field> of $H$.