Solver strategies

The detail strategies related to the Solver option guides the search-algorithm and to optimize a schedule more effectively.

The Priority Batches field defines a sub-selection of batches in the user defined selection. This field displays a list of predefined and named searches. These can be defined by saving a user-defined selection in Batches > Process Batches or Batches > Tank Batches.

The set of batches that are to be sequenced is defined as the intersection of the current selection (selected batches on the planning board) and the priority batches. Sequencing enables the solver to apply different sequences only for these set of batches. Other batches in the current selection (batches that are not available in the set of priority tank batches or in the set of priority process batches) follow the order set by the placement of the priority batches. The order of non-priority batches is determined by the order of the priority batches; when a sequence for priority batches is selected, the order of non-priority batches is not modified. In most cases, priority batches include or comprise the batches that form the bottleneck in a factory.

• priority process batches

  This field displays a list sub-selection of the process batches in the current user-defined selection. By default, all selected process batches are indicated as priority batches. Other selections can be defined through Batches > Process Batches by saving a named search.

  Note: You can select empty selection, if you do not require priority process batches.
• Priority Tank Batches

  This field displays a list of sub-selection of the tank batches in the current user-defined selection. By default, all selected tank batches are indicated as priority batches. Other selections can be defined through Batches > Tank batches.

  Note: You can select empty selection, if you do not require priority tank batches.
• sequence priority batches

  If this check box is selected, the Solver schedules the selected priority batches in a specific predefined sequence, instead of trying all possible sequences for a feasible or optimal schedule. A single sequence can be used to limit the search space, when the optimal sequence is known in advance or when the user require to enforce some specific sequence. The list displays a number of predefined sequences, possibly extended by a user-defined sequence.

  Note: This strategy includes backtracking on time and enabling resource allocation decisions.
• strict sequence (do not fill gaps)

  If strict sequence is selected, the selected sequence is not interrupted. The sequence can contains large gaps, wherein other batches cannot fit.

• first allocate then sequence

  By default, the Solver schedules each batch (piece by piece), setting the time and assigning a resource simultaneously. If this check box is selected, the Solver first allocate all batches to some valid resource and determine the best sequence and time values for each batch based on the allocation. Setting the allocations in advance drastically limits the search space, so this strategy enables the Solver to find a solution efficiently. Since all allocations are not considered, a feasible schedule cannot be found even though one allocation exist. This check box is used in case of complex overlapping Resource groups or Choice groups containing heterogeneous resources with intricate changeovers. Therefore, enables you to optimize changeover.