def __revise_i(constraint_problem: ConstraintProblem, subset: Tuple[Variable, ...], ith_variable: Variable,
i_subsets_consistent_assignments: Dict[Tuple[Tuple[Variable, ...], Variable], set]) -> bool:
revised = False
i_subsets_constraints = map(constraint_problem.get_constraints_containing_variable, subset)
i_subsets_constraints = set(chain.from_iterable(i_subsets_constraints))
i_subsets_constraints.update(constraint_problem.get_constraints_containing_variable(ith_variable))
subset_domain = [variable.domain for variable in subset]
for assignment in product(*subset_domain):
var_were_assigned = dict()
for variable, value in zip(subset, assignment):
variable_was_assigned = False if variable.value is None else True
var_were_assigned[variable] = variable_was_assigned
if not variable_was_assigned:
variable.assign(value)
ith_variable_was_assigned = False if ith_variable.value is None else True
for value in ith_variable.domain:
if not ith_variable_was_assigned:
ith_variable.assign(value)
for constraint in i_subsets_constraints:
i_assignment = assignment + (value,)
if not constraint.is_consistent() and i_assignment in i_subsets_consistent_assignments[(subset,
ith_variable)]:
revised = True
i_subsets_consistent_assignments[(subset, ith_variable)].remove(i_assignment)
if not ith_variable_was_assigned:
ith_variable.unassign()
for variable in subset:
if not var_were_assigned[variable]:
variable.unassign()
__reduce_assignment_constraints_domains(constraint_problem, i_subsets_consistent_assignments)
return revised
def __revise(constraints_problem: ConstraintProblem, variable: Variable,
neighbor: Variable) -> bool:
if variable.value is not None:
return False
variable_constraints = constraints_problem.get_constraints_containing_variable(
variable)
neighbor_constraints = constraints_problem.get_constraints_containing_variable(
neighbor)
shared_constraint, *_ = (variable_constraints & neighbor_constraints)
revised = False
for value in variable.domain:
variable.assign(value)
if not shared_constraint.get_consistent_domain_values(neighbor):
variable.remove_from_domain(value)
revised = True
variable.unassign()
return revised
def __calculate_weight(constraint_problem: ConstraintProblem,
constraints_weights: Dict[Constraint, int]) -> int:
weight = 0
for variable in constraint_problem.get_variables():
unsatisfied_constraints = filterfalse(
None,
constraint_problem.get_constraints_containing_variable(variable))
for unsatisfied_const in unsatisfied_constraints:
weight += constraints_weights[unsatisfied_const]
return weight