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improve performance on sat solver

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This commit is contained in:
Laurent Perron
2017-05-16 10:43:07 +02:00
parent d2cd773edb
commit f8246cd16d
11 changed files with 521 additions and 232 deletions
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26
ortools/sat/integer_expr.cc
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@@ -94,9 +94,27 @@ bool IntegerSumLE::Propagate() {
const IntegerValue new_lb = rev_lb_fixed_vars_ + lb_unfixed_vars;
// Conflict?
const IntegerValue slack = upper_bound_ - new_lb;
IntegerValue slack = upper_bound_ - new_lb;
if (slack < 0) {
FillIntegerReason();
// Like FillIntegerReason() but try to relax the reason a bit.
//
// TODO(user): if not all the slack is consumed, we could relax it even
// more. It might also be advantageous to relax first the variable with the
// highest "trail index".
integer_reason_.clear();
for (int i = 0; i < vars_.size(); ++i) {
const IntegerVariable var = vars_[i];
const IntegerValue lb = integer_trail_->LowerBound(var);
const IntegerValue prev_lb = integer_trail_->PreviousLowerBound(var);
if (lb == prev_lb) continue; // level zero.
const IntegerValue diff = (lb - prev_lb) * coeffs_[i];
if (slack + diff < 0) {
integer_reason_.push_back(IntegerLiteral::GreaterOrEqual(var, prev_lb));
slack += diff;
} else {
integer_reason_.push_back(IntegerLiteral::GreaterOrEqual(var, lb));
}
}
// Reified case: If the reified literal is unassigned, we set it to false,
// otherwise we have a conflict.
@@ -132,9 +150,7 @@ bool IntegerSumLE::Propagate() {
FillIntegerReason();
}
// We need to remove the entry index from the reason temporarily. This is
// OK with the reversible aspect of integer_reason_ because fixed
// variables will never be swapped.
// We need to remove the entry index from the reason temporarily.
IntegerLiteral saved;
const int index = index_in_integer_reason_[i];
if (index >= 0) {