Features

• It is a framework for branching, cutting, pricing, and propagation.
• It is highly flexible through many possible user plugins:
  • constraint handlers to implement arbitrary constraints,
  • variable pricers to dynamically create problem variables,
  • domain propagators to apply constraint independent propagations on the variables' domains,
  • cut separators to apply cutting planes on the LP relaxation,
  • relaxators to provide relaxations and dual bounds in addition to the LP relaxation,
  • primal heuristics to search for feasible solutions with specific support for probing and diving,
  • node selectors to guide the search,
  • branching rules to split the problem into subproblems,
  • presolvers to simplify the solved problem,
  • file readers to parse different input file formats,
  • event handlers to be informed on specific events, e.g., when a node was solved, a specific variable changed its bounds, or a new primal solution was found,
  • display handlers to create additional columns in the solver's output.
  • dialog handlers to extend the included command shell.
• Every existing unit is implemented as a plugin, leading to an interface flexible enough to meet the needs of most additional user extensions.
• A dynamic cut pool management is included.
• The user may mix preprocessed and active problem variables in expressions: they are automatically transformed to corresponding active problem variables.
• Arbitrarily many children per node can be created, and the different children can be arbitrarily defined.
• It has an open LP solver support. It currently supports:
  • ILOG CPLEX
  • Dash XPress-MP
  • Mosek
  • SoPlex
  • CLP.
• The LP relaxation need not to be solved at every single node (it can even be turned off completely, mimicing a pure constraint solver).
• Additional relaxations (e.g., semidefinite relaxations or Lagrangian relaxations) can be included, working in parallel or interleaved.
• Conflict analysis can be applied to learn from infeasible subproblems.
• Dynamic memory management reduces the number of operation system calls with automatic memory leakage detection in debug mode.