Constrained optimization through fixed point techniques
  We introduce an alternative approach for constrained mathematical programming problems. It rests on two main aspects: an efficient way to compute optimal solutions for unconstrained problems, and multipliers regarded as variables for a certain map. Contrary to typical dual strategies, optimal vectors of multipliers are sought as fixed points for that map. Two distinctive features are worth highlighting: its simplicity and flexibility for the implementation, and its convergence properties. 
Pablo Pedregal
math.OC