#20351: sage.libs.ppl.MIP_Problem: Add support for integer variables
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Reporter: mkoeppe | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-7.2
Component: numerical | Resolution:
Keywords: lp | Merged in:
Authors: Matthias Koeppe | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/mkoeppe/sage_libs_ppl_mip_problem_and_pplbackend__add_support_for_integer_variables|
9f35b65ae443d565bcf53319fc57751baf640fc8
Dependencies: | Stopgaps:
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Comment (by mkoeppe):
> Are indices of variables 0-based, 1-based?
> Could this info be added to docs?
This is already documented in the class docstring of `Variable`. (It's
0-based.)
> Can one use this to generate integer hull of a polytope defined by
inequalities (perhaps after adjusting the corresponding Polyhedron code)?
> Or is this optimisation-only thing?
No, PPL does not have code for computing integer hulls.
The closest that there is in the polyhedron code is the following
interesting function:
{{{
void
Parma_Polyhedra_Library::Polyhedron::drop_some_non_integer_points(Complexity_Class
complexity = ANY_COMPLEXITY)
Possibly tightens *this by dropping some points with non-integer
coordinates.
}}}
I would be quite interested in having code in Sage that computes a
polyhedron given only by a linear optimization oracle [for example,
implemented by a MIP solver], see for example
http://arxiv.org/pdf/1412.3987.pdf. But this has nothing to do with this
ticket.
--
Ticket URL: <http://trac.sagemath.org/ticket/20351#comment:12>
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