fix: compute a single IIS in Xpress infeasibility path#658
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FabianHofmann merged 1 commit intomasterfrom Apr 21, 2026
Merged
fix: compute a single IIS in Xpress infeasibility path#658FabianHofmann merged 1 commit intomasterfrom
FabianHofmann merged 1 commit intomasterfrom
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Previously `_compute_infeasibilities_xpress` called `iisall()` and merged every IIS into one deduplicated set, losing per-IIS grouping. Switch to `firstIIS(2)` (with `iisfirst(2)` fallback) so a single IIS is returned, matching the Gurobi behavior.
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would like to make a patch release with this and #605 |
coroa
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Apr 20, 2026
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Changes proposed in this Pull Request
Model._compute_infeasibilities_xpressnow computes a single IIS viafirstIIS(2)(new Xpress API) withiisfirst(2)as deprecated-API fallback, instead of callingiisall()and iterating every IIS.set, flattening per-IIS grouping and returning an ambiguous union. With only one IIS computed, the returnedlist[int]matches the Gurobi path's semantics.2asks Xpress for a proper IIS optimised for a quick result (mode0would return a non-minimal infeasible subproblem; mode1optimises for minimality at higher cost).Upcoming Version.Checklist
doc.doc/release_notes.rstof the upcoming release is included.