Avoid postsolve after sparsify may have been used in presolve - #2500
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…educes the model to empty
fwesselm
approved these changes
Aug 18, 2025
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Interesting presolve issue, exposed when the analytic centre calculation (using IPM without crossover) reduced the LP to empty.
Now handling the case when no basic solution is required - such as when using PDLP or IPM without crossover - in which case sparsify is permitted. However, previously, if presolve reduces the model to empty an empty basis would be set up regardless, and passed to postsolve. Now any basis is invalidated before postsolve if no basic solution is required.