# Package org.optaplanner.core.impl.solver

- Interface Summary
  Interface | Description
  --- | ---
  ProblemFactChange<Solution_> | A ProblemFactChange represents a change in 1 or more problem facts of a `PlanningSolution`.

- Class Summary
  Class | Description
  --- | ---
  AbstractSolver<Solution_> | Common code between `DefaultSolver` and child solvers (such as `PartitionSolver`.
  DefaultSolver<Solution_> | Default implementation for `Solver`.
  DefaultSolverFactory<Solution_> |
  DefaultSolverJob<Solution_,​ProblemId_> |
  DefaultSolverManager<Solution_,​ProblemId_> |