Changeset 1853 for trunk/Cbc/README
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 Jan 27, 2013 12:51:17 PM (9 years ago)
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trunk/Cbc/README
r1850 r1853 44 44 probability of finding an improved solution by flipping a small number of binary variables), in particular 45 45 when it is applied to the first heuristic solutions found at the root node. 46 47 46 5. An implementation of ZeroHalfCuts by Alberto Caprara is now available. 48 47 By default, these cuts are off. To use add to your command line zerohalfCuts root (or other options) or just zero. … … 53 52 âEmbedding Cuts in a Branch and Cut Framework: a Computational Study with {0,1/2}Cutsâ 54 53 INFORMS Journal on Computing 19(2), 229238, 2007 54 6. Allow initialization of random seed by user. Pseudorandom 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 pseudorandom 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. 60 7. 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. 65 55 66 56 67
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