Changeset 1853 for trunk/Cbc/README

Jan 27, 2013 12:51:17 PM (9 years ago)

update README

1 edited


  • trunk/Cbc/README

    r1850 r1853  
    4444   probability of finding an improved solution by flipping a small number of binary variables), in particular
    4545   when it is applied to the first heuristic solutions found at the root node.
    47465. An implementation of Zero-Half-Cuts by Alberto Caprara is now available.
    4847   By default, these cuts are off.  To use add to your command line -zerohalfCuts root (or other options) or just -zero.
    5352   â€œEmbedding Cuts in a Branch and Cut Framework: a Computational Study with {0,1/2}-Cuts”
    5453   INFORMS Journal on Computing 19(2), 229-238, 2007
     546.  Allow initialization of random seed by user.  Pseudo-random numbers are used in Cbc and Clp.  In Clp they
     55   are used to break ties in degenerate problems, while in Cbc heuristics such as the Feasibility Pump use them   
     56   to decide whether to round up or down.  So if a different pseudo-random seed is given to Clp then you may get
     57   a different continuous optimum and so different cuts and heuristic solutions. This can be switched on by
     58   setting randomSeed for Clp and/or randomCbcSeed for Cbc.  The special value of 0 tells code to use time of day
     59   for initial seed.
     607.  Building on this idea Andrea Lodi , Matteo Fischetti , Michele Monaci , Domenico Salvagnin and Andrea Tramontani
     61   suggest that this idea be be improved by running at the root node with multiple copies of solver, each
     62   with its own different seed and then passing in the solutions and cuts so that the main solver has a richer
     63   set of solutions and possibly stronger cuts.  This is switched on by setting multipleRootPasses.  These can also
     64   be done in parallel.
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