Remove removeSlacks - #3309
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Remove removeSlacks#3309
removeSlacks#3309Conversation
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September 21, 2026 13:31
…is covered by zeroCostSingleton
…plication of zeroCostSingleton reduction
Opt-Mucca
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Sep 21, 2026
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Looks good! I support removing dead code.
added 2 commits
September 21, 2026 15:16
…ection to HPresolveAnalysis::analysePresolveRuleLog
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Spurious CI failures, since changes are removal of code |
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Description
Fuzzing identified an error in a dual value when the
removeSlackspresolve reduction was used.The
removeSlackspresolve reduction cannot be used when the cost is nonzero, since dual postsolve cannot be computed (due to the objective substitution changing basic costs so the row duals can't be maintained in postsolve). WhenremoveSlacksis restricted to zero cost column singletons, it's a duplicate of thezeroCostSingletonreduction.Note that the
removeSlackspresolve reduction was off by default - controlled by thepresolve_remove_slacksoption - because it didn't seem to be valuable for LPs. Thepresolve_remove_slacksoption has been retained - albeit with "redundant option!" added to its description, since removing it would be a breaking change.Checklist
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