# Curve Evolution

1. Mar 17, 2005

Hi all,
The Epstein Gage Lemma states that a curve evolving under some given velocity vector V (V = VnN + VtT), where Vn is the normal velocity component and Vt is the tangential velocity component, N is the normal to the curve and T is the tangent to the curve, will give the same curves if evolved under only Vn, i.e. the normal velocity component. The Tangential component Vt affects only the parameterisation and not the shape of the curve.

Can somebody give me a simple enough proof of the above theorem?