Hight-order Noether's Theorem for Nonsmooth Extremals of Isoperimetric   Variational Problems with Time Delay
  We obtain a nonsmooth higher-order extension of Noether's symmetry theorem for variational isoperimetric problems with delayed arguments. The result is proved to be valid in the class of Lipschitz functions, as long as the delayed higher-order Euler--Lagrange extremals are restricted to those that satisfy the delayed higher-order DuBois--Reymond necessary optimality condition. The important case of delayed isoperimetric optimal control problems is considered as well. 
G. S. F. Frederico and M. J. Lazo
math.OC math-ph math.MP