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Fix original constraint duals and presolve consistency - #1256
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Joao-Dionisio merged 9 commits intoOct 18, 2026
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getDualsolKnapsack and getDualfarkasKnapsack looked up the transformed constraint the wrong way round, so an original constraint was passed to SCIP directly and the dual came back as 0. Follow the linear versions instead, and return 0 when presolve has removed the constraint and there is no transformed one to read from. getVarsAnd asserted a two-element tuple, which never fails. Drop the parentheses so a non-AND constraint is rejected.
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
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+ Coverage 57.91% 57.93% +0.02%
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Hey @mohitt31 , thank you for your contribution, and I'm sorry for taking so long! Now it'll be much easier to keep control of the repo.
I think it'd be better if the other methods returned 0 as well. |
Match the knapsack accessors when presolve removes the transformed constraint. Cover dual and Farkas accessors for all three handlers and document the behavior.
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Thank you so much @mohitt31 !!
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getDualsolKnapsack()andgetDualfarkasKnapsack()looked up the wrong constraint representation, so passing an original binding constraint returned zero instead of its transformed constraint's dual. Both now retrieve the transformed constraint before calling SCIP.getVarsAnd()also used a tuple assertion that could never fail; the assertion now rejects non-AND constraints.When presolve removes a constraint's transformed counterpart, the linear, logicor and knapsack dual/Farkas accessors consistently return
0.0, as requested in review. The linear and logicor methods no longer try to wrap a nullSCIP_CONS*in a Python Constraint. The behavior is documented and recorded in the changelog.Tests cover nonzero knapsack dual/Farkas values through original and transformed constraints, rejection of a non-AND constraint, and all six combinations of linear/logicor/knapsack dual/Farkas accessors after presolve removes the transformed constraint. The new removed-constraint tests reproduced four failures before the consistency fix, while the two knapsack cases already passed.
Validation with SCIP 10.0.3 on macOS/ARM64: full test suite 477 passed, 108 skipped, 11 xfailed;
tests/test_cons.py33 passed, 1 xfailed. Built the Cython extension against the local SCIP library.git diff --checkpasses.Follow-up to the review on #1255.