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Decrease probing budget after some limit #2512

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Merged
merged 4 commits into from
Sep 5, 2025
Merged

Decrease probing budget after some limit #2512

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4c3c98d
Tighten budget after 1000 cols probed on
Opt-Mucca Aug 18, 2025
a684943
Add updated rule
Opt-Mucca Aug 18, 2025
664600c
Update rule to be more conservative
Opt-Mucca Aug 20, 2025
c47a396
Formatting
Opt-Mucca Aug 21, 2025
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16 changes: 12 additions & 4 deletions highs/presolve/HPresolve.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1545,12 +1545,20 @@ HPresolve::Result HPresolve::runProbing(HighsPostsolveStack& postsolve_stack) {
if (cliquetable.getSubstitution(i) != nullptr || !domain.isBinary(i))
continue;

bool tightenLimits = (numProbed - oldNumProbed) >= 2500;

// when a large percentage of columns have been deleted, stop this round
// of probing
// if (numDel > std::max(model->num_col_ * 0.2, 1000.)) break;
probingEarlyAbort =
numDel >
std::max(HighsInt{1000}, (model->num_row_ + model->num_col_) / 20);
if (!tightenLimits) {
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This is a question of taste, but if you would want to avoid the if-else, you could have the following here:

     bool tightenLimits = (numProbed - oldNumProbed) >= 2500;
     HighsInt multiplier = tightenLimits ? -1 : 1;
     // when a large percentage of columns have been deleted, stop this round
     // of probing
     // if (numDel > std::max(model->num_col_ * 0.2, 1000.)) break;
     probingEarlyAbort =
         numDel >
         multiplier *
             std::max(multiplier * HighsInt{1000},
                      multiplier * (model->num_row_ + model->num_col_) / 20);
     if (probingEarlyAbort) break;

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Sorry for missing this comment! I'm happy with if-else logic. I find it easier to read than the double multiplier.

probingEarlyAbort =
numDel >
std::max(HighsInt{1000}, (model->num_row_ + model->num_col_) / 20);
} else {
probingEarlyAbort =
numDel >
std::min(HighsInt{1000}, (model->num_row_ + model->num_col_) / 20);
}
if (probingEarlyAbort) break;

// break in case of too many new implications to not spent ages in
Expand Down Expand Up @@ -1597,7 +1605,7 @@ HPresolve::Result HPresolve::runProbing(HighsPostsolveStack& postsolve_stack) {
numDel = newNumDel;
numFail = 0;
} else if (mipsolver->submip || numNewCliques == 0) {
splayContingent -= 100 * numFail;
splayContingent -= (tightenLimits ? 250 : 100) * numFail;
++numFail;
} else {
splayContingent += 1000 * numNewCliques;
Expand Down
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