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Section: New Software and Platforms

BaPCod – a generic Branch-and-Price Code

Participants : Issam Tahiri [Software Engineer] , François Clautiaux, Boris Detienne, Pierre Pesneau, Ruslan Sadykov, François Vanderbeck [correspondant] .

BaPCod is a prototype code that solves Mixed Integer Programs (MIP) by application of decomposition and reformulation approach (relying mostly on Dantzig-Wolfe reformulation techniques). The reformulated problem is solved using a branch-and-price-and-cut (column and cut generation) algorithm. This software platform, made of C++ classes, offers a “black-box” implementation that does not require user input and is not application specific. The features are

$\left(i\right)$ A modeling language to express a compact integer linear programming model of the application on hand.

$\left(ii\right)$ the automation of the Dantzig-Wolfe reformulation process. The user can provide subproblem solvers if available, but he does not need to explicitly define the reformulation, the explicit form of the columns, their reduced cost, or the Lagrangian bounds.

$\left(iii\right)$ a default column generation procedure with standard initialization and stabilization [1] , [56] [88] [87] [77] and

$\left(iv\right)$ a default branching scheme that is generic to all applications [7] ,

$\left(v\right)$ default primal heuristics specially developed for use in a decomposition framework [61] , [76] , [89] .

The prototype software was/is used as background solver in our application studies and local PhD thesis. It also serves as the framework for our comparative study in a Inria assocaited team project and our transfert projects (the prototype enables us to be very responsive in our industrial contact).

See also the web page https://wiki.bordeaux.inria.fr/realopt/pmwiki.php/Project/BaPCod .