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polish CP-SAT cut management code

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This commit is contained in:
Laurent Perron
2020-03-03 17:06:35 +01:00
parent d7703bc106
commit 6e4944b9e2
3 changed files with 6 additions and 15 deletions
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16
ortools/sat/linear_constraint_manager.cc
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@@ -149,7 +149,6 @@ LinearConstraintManager::ConstraintIndex LinearConstraintManager::Add(
ct_info.objective_parallelism_computed = false;
ct_info.objective_parallelism = 0.0;
ct_info.inactive_count = 0;
ct_info.permanently_removed = false;
ct_info.hash = key;
equiv_constraints_[key] = ct_index;
@@ -383,8 +382,6 @@ bool LinearConstraintManager::ChangeLp(
// ones that are currently not satisfied by at least "tolerance".
const double tolerance = 1e-6;
for (ConstraintIndex i(0); i < constraint_infos_.size(); ++i) {
if (constraint_infos_[i].permanently_removed) continue;
// Inprocessing of the constraint.
if (simplify_constraints &&
SimplifyConstraint(&constraint_infos_[i].constraint)) {
@@ -491,7 +488,6 @@ bool LinearConstraintManager::ChangeLp(
}
const ConstraintIndex new_constraint = new_constraints[j];
if (constraint_infos_[new_constraint].permanently_removed) continue;
if (constraint_infos_[new_constraint].is_in_lp) continue;
if (last_added_candidate != kInvalidConstraintIndex) {
@@ -505,15 +501,13 @@ bool LinearConstraintManager::ChangeLp(
std::min(new_constraints_orthogonalities[j], current_orthogonality);
}
// NOTE(user): It is safe to permanently remove this constraint as the
// constraint that is almost parallel to this constraint is present in the
// LP or is inactive for a long time and is removed from the LP. In either
// case, this constraint is not adding significant value and is only
// making the LP larger.
// NOTE(user): It is safe to not add this constraint as the constraint
// that is almost parallel to this constraint is present in the LP or is
// inactive for a long time and is removed from the LP. In either case,
// this constraint is not adding significant value and is only making the
// LP larger.
if (new_constraints_orthogonalities[j] <
sat_parameters_.min_orthogonality_for_lp_constraints()) {
constraint_infos_[new_constraint].permanently_removed = true;
VLOG(2) << "Constraint permanently removed: " << new_constraint;
continue;
}

3
ortools/sat/linear_constraint_manager.h
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@@ -49,9 +49,6 @@ class LinearConstraintManager {
double objective_parallelism;
bool objective_parallelism_computed;
bool is_in_lp;
// A constraint might be marked for permanent removal if it is almost
// parallel to one of the existing constraints in the LP.
bool permanently_removed;
size_t hash;
double current_score;
};

2
ortools/sat/sat_parameters.proto
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@@ -595,7 +595,7 @@ message SatParameters {
// constraints during current call. Orthogonality is defined as 1 -
// cosine(vector angle between constraints). A value of zero disable this
// feature.
optional double min_orthogonality_for_lp_constraints = 115 [default = 0.0];
optional double min_orthogonality_for_lp_constraints = 115 [default = 0.05];
// Max number of time we perform cut generation and resolve the LP at level 0.
optional int32 max_cut_rounds_at_level_zero = 154 [default = 1];