> I wonder if there are any plans for GLPK to provide an interface to the > COIN-OR CGL cut generator library in order to provide better/deeper cuts > in MIP optimization? (CGL is licensed under the CPL which is similar > to the LGPL)
There are too many problems. First, GLPK is covered by GNU GPL, and I am not sure that CPL is compatible with GPL. Second, GLPK is written entirely in C while COIN software in C++. Third, currently GLPK has no features to implement branch-and-cut. The latter is a cruicial point. Now I am working on implementation of a new module for the basis factorization (which is based on the Schur complement); it will allow efficiently updating the factorization on adding/changing/deleting rows and columns and, in turn, will allow (among other advantages) implementing basic operations for branch-and-cut. > In my experience the CBC solver form the COIN-OR people, which uses CGL > library to generate cuts is much faster than GLPK on MIP problems and > even solves problems GLPK fails to solve. If you need an example > problems, I can provide some. Yes, branch-and-bound cannot compet with branch-and-cut on some classes of hard combinatorial optimization problems. > I would prefer to use GLPK for its good support of MathProg and ease of > use (CBC can only read MPS files and has no modelling support). It seems to me that the GLPK MathProg translator is available from COIN solvers. Andrew Makhorin _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
