Chips-n-Salsa, v2.7.0

[2.7.0] - 2021-2-25

Added

• Added HybridConstructiveHeuristic, which provides the ability
  to use multiple heuristics with a stochastic sampling search,
  where a heuristic is chosen from a set of constructive heuristics
  at the start of each iteration of the stochastic sampler and used
  for all decisions made during that iteration. The class supports the
  following strategies for selecting the next heuristic:
  • Heuristic uniformly at random from among the available heuristics.
  • Heuristic chosen using a round robin strategy that systematically cycles
    over the heuristics.
  • Heuristic chosen via a weighted random selection process.
• Added versions of a few constructive heuristics for
  scheduling problems that precompute heuristic values
  upon construction of the heuristic. Many of the scheduling
  heuristic implementations already do this, where it is
  possible to do so, provided the memory and time requirements
  for precomputing heuristic values is linear in the number
  of jobs. Some heuristics that consider setup times, however,
  need quadratic memory if the heuristic is precomputed prior
  to running the search. The existing implementations of these
  compute the heuristic as it is needed during the search,
  which means for a stochastic sampler with many iterations
  that the same heuristic values will be computed repeatedly.
  We've added versions of these that precompute the heuristic
  values so that if your problem is small enough to afford the
  quadratic memory, and if you will be running enough iterations
  of the stochastic sampler to afford the quadratic time of
  this precomputation step, then you can choose to use a
  precomputed version.
  • A scheduling heuristic, SmallestSetupPrecompute, which is
    a version of SmallestSetup, but which precomputes a table
    of heuristic values to avoid recomputing the same heuristic
    values repeatedly across multiple iterations of a stochastic
    sampling search.
  • A scheduling heuristic, ShortestProcessingPlusSetupTimePrecompute, which is
    a version of ShortestProcessingPlusSetupTime, but which precomputes a table
    of heuristic values to avoid recomputing the same heuristic
    values repeatedly across multiple iterations of a stochastic
    sampling search.
  • A scheduling heuristic, WeightedShortestProcessingPlusSetupTimePrecompute, which is
    a version of WeightedShortestProcessingPlusSetupTime, but which precomputes a table
    of heuristic values to avoid recomputing the same heuristic
    values repeatedly across multiple iterations of a stochastic
    sampling search.

Changed

• Dependency updated to JPT v2.4.0.