Solver interfaces (cpmpy.solvers)

Solver interfaces have the same API as Model. However some solvers are incremental, meaning that after solving a problem, you can add constraints or change the objective, and the next solve will reuse as much information from the previous solve as possible. Some clause learning solvers also support solving with assumptions, meaning you can solve the same problem with different assumption variables toggled on/off, and the solver will reuse information from the previous solves.

See Supported solvers for the list of solvers and their capabilities.

To benefit from incrementality, you have to instantiate the solver object and reuse it, rather than working on a Model object. Solvers must be instantiated throught the static cp.SolverLookup class:

• cp.SolverLookup.solvernames() – List all installed solvers (including subsolvers).

• cp.SolverLookup.get(solvername, model=None) – Initialize a specific solver.

For example creating a CPMpy solver object for OR-Tools:

import cpmpy as cp
s = cp.SolverLookup.get("ortools")
# can now use solver object 's' over and over again

List of solver submodules

ortools	Interface to OR-Tools' CP-SAT Python API.
choco	Interface to Choco solver's Python API.
gcs	Interface to the Glasgow Constraint Solver's API for the CPMpy library.
minizinc	Interface to MiniZinc's Python API.
cpo	Interface to CP Optimizer's Python API.
gurobi	Interface to Gurobi Optimizer's Python API.
exact	Interface to Exact's Python API
z3	Interface to Z3's Python API.
pysat	Interface to PySAT's API
pysdd	Interface to PySDD's API
pindakaas	Interface to the Pindakaas solver's Python API.
pumpkin	Interface to Pumpkin's API
cplex	Interface to CPLEX Optimizer using the python 'docplex.mp' package
hexaly	Interface to Hexaly's API
rc2	Interface to PySAT's RC2 MaxSAT solver API

List of helper submodules

solver_interface	Generic interface, solver status and exit status.
utils	Utilities for handling solvers

List of functions

param_combinations

Recursively yield all combinations of param values