Opened 7 years ago
Last modified 20 months ago
#19523 new defect
Adding constraints for the wrong MILP crashes Sage — at Version 5
Reported by: | Jeroen Demeyer | Owned by: | |
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Priority: | major | Milestone: | sage-7.3 |
Component: | linear programming | Keywords: | |
Cc: | Yuan Zhou | Merged in: | |
Authors: | Reviewers: | ||
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | #19525 | Stopgaps: |
Description (last modified by )
sage: p = MixedIntegerLinearProgram(solver="glpk") sage: q = MixedIntegerLinearProgram(solver="glpk") sage: q.add_constraint(p[0] <= 1) ------------------------------------------------------------------------ Unhandled SIGABRT: An abort() occurred in Sage. This probably occurred because a *compiled* component of Sage has a bug in it and is not properly wrapped with sig_on(), sig_off(). Sage will now terminate. ------------------------------------------------------------------------
With #19525, this improves to not crashing Sage:
sage: sage: p = MixedIntegerLinearProgram(solver="glpk") sage: sage: q = MixedIntegerLinearProgram(solver="glpk") sage: sage: q.add_constraint(p[0] <= 1) --------------------------------------------------------------------------- GLPKError Traceback (most recent call last) ... GLPKError: glp_set_mat_row: i = 1; len = 1; invalid row length Error detected in file glpapi01.c at line 760
This ticket is to actually fix the error completely or give a better error message.
Also a crash with the COIN backend.
And low-level error message with the PPL and InteractiveLP (#20296 ) backends.
The CVX backend silently adds a new variable that is accessible only to the backend:.
sage: sage: default_mip_solver("cvxopt") sage: sage: p = MixedIntegerLinearProgram() sage: sage: q = MixedIntegerLinearProgram() sage: sage: q.add_constraint(p[0] <= 1) sage: q.number_of_variables() 1
Change History (5)
comment:1 Changed 7 years ago by
Dependencies: | → #19525 |
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Description: | modified (diff) |
comment:2 Changed 7 years ago by
Cc: | Nathann Cohen added |
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comment:3 Changed 7 years ago by
Description: | modified (diff) |
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Priority: | critical → major |
comment:4 Changed 7 years ago by
comment:5 Changed 7 years ago by
Description: | modified (diff) |
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While
MIPVariable
objects know which MIP they belong to, their "components" gotten byp[0]
etc. are elements ofLinearFunctionsParent(base_ring)
, and do not remember their MIP (nor even their name). So with the current design it does not seem possible to catch the error of adding constraints to the wrong MIP. So unfortunately only lower-level error checking, catching out-of-bounds indices, is possible.