document: Elastic constraint branching , the Wedelin/Carmen Lagrangian heuristic and integer programming for personnel scheduling The Wedelin algorithm is a Lagrangian based heuristic that is being successfully used by Carmen Systems to solve large crew pairing problems within the airline industry . We extend the Wedelin approach by developing an implementation for personnel scheduling problems -LRB- also termed staff rostering problems -RRB- that exploits the special structure of these problems . We also introduce elastic constraint branching with the twin aims of improving the performance of our new approach and making it more column generation friendly . Numerical results show that our approach can outperform the commercial solver CPLEX on difficult commercial rostering problems
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