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[CP-SAT] tweak to lb_tree_search

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This commit is contained in:
Laurent Perron
2021-11-04 18:58:34 +01:00
parent 89dc88bfdd
commit 3b745ab2c1
4 changed files with 64 additions and 52 deletions
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42
ortools/sat/integer_expr.cc
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@@ -77,16 +77,11 @@ void IntegerSumLE::FillIntegerReason() {
}
std::pair<IntegerValue, IntegerValue> IntegerSumLE::ConditionalLb(
IntegerVariable bool_view, IntegerVariable target_var) const {
if (integer_trail_->LowerBound(bool_view) != 0 &&
integer_trail_->UpperBound(bool_view) != 1) {
return {kMinIntegerValue, kMinIntegerValue};
}
IntegerLiteral integer_literal, IntegerVariable target_var) const {
// Recall that all our coefficient are positive.
bool bool_view_present = false;
bool bool_view_present_positively = false;
IntegerValue view_coeff;
bool literal_var_present = false;
bool literal_var_present_positively = false;
IntegerValue var_coeff;
bool target_var_present_negatively = false;
IntegerValue target_coeff;
@@ -104,21 +99,34 @@ std::pair<IntegerValue, IntegerValue> IntegerSumLE::ConditionalLb(
const IntegerValue lb = integer_trail_->LowerBound(var);
implied_lb += coeff * lb;
if (PositiveVariable(var) == PositiveVariable(bool_view)) {
view_coeff = coeff;
bool_view_present = true;
bool_view_present_positively = (var == bool_view);
if (PositiveVariable(var) == PositiveVariable(integer_literal.var)) {
var_coeff = coeff;
literal_var_present = true;
literal_var_present_positively = (var == integer_literal.var);
}
}
if (!bool_view_present || !target_var_present_negatively) {
if (!literal_var_present || !target_var_present_negatively) {
return {kMinIntegerValue, kMinIntegerValue};
}
if (bool_view_present_positively) {
// A literal means var >= bound.
if (literal_var_present_positively) {
// We have var_coeff * var in the expression, the literal is var >= bound.
// When it is false, it is not relevant as implied_lb used var >= lb.
// When it is true, the diff is bound - lb.
const IntegerValue diff = std::max(
IntegerValue(0), integer_literal.bound -
integer_trail_->LowerBound(integer_literal.var));
return {CeilRatio(implied_lb, target_coeff),
CeilRatio(implied_lb + view_coeff, target_coeff)};
CeilRatio(implied_lb + var_coeff * diff, target_coeff)};
} else {
return {CeilRatio(implied_lb + view_coeff, target_coeff),
// We have var_coeff * -var in the expression, the literal is var >= bound.
// When it is true, it is not relevant as implied_lb used -var >= -ub.
// And when it is false it means var < bound, so -var >= -bound + 1
const IntegerValue diff = std::max(
IntegerValue(0), integer_trail_->UpperBound(integer_literal.var) -
integer_literal.bound + 1);
return {CeilRatio(implied_lb + var_coeff * diff, target_coeff),
CeilRatio(implied_lb, target_coeff)};
}
}