Multiobjective fractional variational calculus in terms of a combined   Caputo derivative
  The study of fractional variational problems in terms of a combined fractional Caputo derivative is introduced. Necessary optimality conditions of Euler-Lagrange type for the basic, isoperimetric, and Lagrange variational problems are proved, as well as transversality and sufficient optimality conditions. This allows to obtain necessary and sufficient Pareto optimality conditions for multiobjective fractional variational problems. 
Agnieszka B. Malinowska, Delfim F. M. Torres
math.OC