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polish integer reasons

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This commit is contained in:
Laurent Perron
2020-01-20 10:51:53 +01:00
parent 061f5da1f2
commit 45a04053e4
2 changed files with 25 additions and 17 deletions
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39
ortools/sat/integer_expr.cc
View File

@@ -372,7 +372,8 @@ bool LinMinPropagator::PropagateLinearUpperBound(
// Conflict.
integer_trail_->RelaxLinearReason(-slack - 1, reason_coeffs,
&linear_sum_reason);
std::vector<IntegerLiteral> local_reason = integer_reason_;
std::vector<IntegerLiteral> local_reason =
integer_reason_for_unique_candidate_;
local_reason.insert(local_reason.end(), linear_sum_reason.begin(),
linear_sum_reason.end());
return integer_trail_->ReportConflict({}, local_reason);
@@ -380,7 +381,6 @@ bool LinMinPropagator::PropagateLinearUpperBound(
// The lower bound of all the variables except one can be used to update the
// upper bound of the last one.
std::vector<IntegerLiteral> local_reason;
for (int i = 0; i < num_vars; ++i) {
if (max_variations[i] <= slack) continue;
@@ -419,7 +419,8 @@ bool LinMinPropagator::PropagateLinearUpperBound(
propagation_slack, reason_coeffs, trail_indices_reason);
}
// Now add the old integer_reason that triggered this propatation.
for (IntegerLiteral reason_lit : integer_reason_) {
for (IntegerLiteral reason_lit :
integer_reason_for_unique_candidate_) {
const int index = integer_trail_->FindTrailIndexOfVarBefore(
reason_lit.var, trail_index);
if (index >= 0) {
@@ -469,16 +470,16 @@ bool LinMinPropagator::Propagate() {
// the linear reason. But that might change in the future.
const bool use_slack = false;
if (min_of_linear_expression_lb > integer_trail_->LowerBound(min_var_)) {
integer_reason_.clear();
std::vector<IntegerLiteral> local_reason;
for (int i = 0; i < exprs_.size(); ++i) {
const IntegerValue slack = expr_lbs_[i] - min_of_linear_expression_lb;
integer_trail_->AppendRelaxedLinearReason(
(use_slack ? slack : IntegerValue(0)), exprs_[i].coeffs,
exprs_[i].vars, &integer_reason_);
exprs_[i].vars, &local_reason);
}
if (!integer_trail_->Enqueue(IntegerLiteral::GreaterOrEqual(
min_var_, min_of_linear_expression_lb),
{}, integer_reason_)) {
{}, local_reason)) {
return false;
}
}
@@ -491,17 +492,22 @@ bool LinMinPropagator::Propagate() {
const IntegerValue ub_of_only_candidate =
LinExprUpperBound(exprs_[last_possible_min_interval], *integer_trail_);
if (current_min_ub < ub_of_only_candidate) {
integer_reason_.clear();
// For this propagation, we only need to fill the integer reason once at
// the lowest level. At higher levels this reason still remains valid.
if (rev_unique_candidate_ == 0) {
integer_reason_for_unique_candidate_.clear();
// The reason is that all the other interval start after current_min_ub.
// And that min_ub has its current value.
integer_reason_.push_back(min_ub_literal);
for (int i = 0; i < exprs_.size(); ++i) {
if (i == last_possible_min_interval) continue;
const IntegerValue slack = expr_lbs_[i] - (current_min_ub + 1);
integer_trail_->AppendRelaxedLinearReason(
(use_slack ? slack : IntegerValue(0)), exprs_[i].coeffs,
exprs_[i].vars, &integer_reason_);
// The reason is that all the other interval start after current_min_ub.
// And that min_ub has its current value.
integer_reason_for_unique_candidate_.push_back(min_ub_literal);
for (int i = 0; i < exprs_.size(); ++i) {
if (i == last_possible_min_interval) continue;
const IntegerValue slack = expr_lbs_[i] - (current_min_ub + 1);
integer_trail_->AppendRelaxedLinearReason(
(use_slack ? slack : IntegerValue(0)), exprs_[i].coeffs,
exprs_[i].vars, &integer_reason_for_unique_candidate_);
}
rev_unique_candidate_ = 1;
}
return PropagateLinearUpperBound(
@@ -528,6 +534,7 @@ void LinMinPropagator::RegisterWith(GenericLiteralWatcher* watcher) {
}
}
watcher->WatchUpperBound(min_var_, id);
watcher->RegisterReversibleInt(id, &rev_unique_candidate_);
}
PositiveProductPropagator::PositiveProductPropagator(

3
ortools/sat/integer_expr.h
View File

@@ -193,7 +193,8 @@ class LinMinPropagator : public PropagatorInterface {
std::vector<IntegerValue> expr_lbs_;
Model* model_;
IntegerTrail* integer_trail_;
std::vector<IntegerLiteral> integer_reason_;
std::vector<IntegerLiteral> integer_reason_for_unique_candidate_;
int rev_unique_candidate_ = 0;
};
// Propagates a * b = c. Basic version, we don't extract any special cases, and