Master equation for lagrangian gauge symmetries

Using purely Hamiltonian methods we derive a simple differential equation f or the generator of the most general local symmetry transformation of a Lag rangian. The restrictions on the gauge parameters found by earlier approach es are easily reproduced from this equation. We also discuss the connection with the purely Lagrangian approach. The general considerations are applie d to the Yang-Mills theory. (C) 2000 Published by Elsevier Science B.V. All rights reserved.