reduces to a standard Hamilton-Jacobi equation. There are several major

advantages to this formulation. The rst is that (x y t) always remains a

function as long as F is smooth. As the surface  evolves, the curve C may

break, merge, and change topology.-reduces to a standard Hamilton-Jacobi equation. There are several major

advantages to this formulation. The rst is that (x　y　t) always remains a

function as long as F is smooth. As the surface  evolves, the curve C may

break, merge, and change topology.