#18734: Construct an interactive_simplex_method.LPDictionary from a
MixedIntegerLinearProgram
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Reporter: mkoeppe | Owner:
Type: enhancement | Status: new
Priority: major | Milestone: sage-6.8
Component: numerical | Resolution:
Keywords: lp | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: #18685, #18688, #18732, #18733 | Stopgaps:
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Description changed by mkoeppe:
Old description:
> For teaching, presentation, and debugging purposes, it could be powerful
> to have a function that sets up a
> sage.numerical.interactive_simplex_method.LPDictionary
> corresponding to the current basis of a MixedIntegerLinearProgram (with
> all variables real).
>
> (One would probably first set up an InteractiveLPProblemStandardForm from
> a MixedIntegerLinearProgram, and then call its "dictionary" method to
> construct the dictionary.)
>
> #18685 added the prerequisite basis status information for the case of
> the GLPK backend.
> #18688 provides corresponding MixedIntegerLinearProgram methods.
>
> #18732 adds the missing functions for retrieving the data of the
> dictionary (for the GLPK backend).
> #18733 provides corresponding MixedIntegerLinearProgram methods.
New description:
For teaching, presentation, and debugging purposes, it could be powerful
to have a function that sets up a
`sage.numerical.interactive_simplex_method.LPDictionary`
corresponding to the current basis of a `MixedIntegerLinearProgram` (with
all variables real).
The plan is as follows:
- `MixedIntegerLinearProgram`.construct_interactive_lp() return an
interactive LP (by querying the backend for problem data) and a list of
basic variables (by querying the backend for col_stat, row_stat)
- from that information, can make an `LPDictionary` or
`LPRevisedDictionary` by invoking the `dictionary` or `revised_dictionary`
methods.
#18685 added the prerequisite basis status information for the case of the
GLPK backend.
#18688 provides corresponding `MixedIntegerLinearProgram` methods.
Next step:
- a new class, LPBackendDictionary (or something) would avoid
InteractiveLP and rather be tied directly to the backend, using tableau
data query functions such as getBInvArow etc.
#18732 adds the missing functions for retrieving the data of the
dictionary (for the GLPK backend).
#18733 provides corresponding MixedIntegerLinearProgram methods.
Doctests could then test that the LPBackendDictionary and the LPDictionary
are the same.
--
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Ticket URL: <http://trac.sagemath.org/ticket/18734#comment:4>
Sage <http://www.sagemath.org>
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