Fix use of MixedIntegerLinearProgram in sage.graphs.graph - part 1

[dcoudert]

Part of #32191 (Meta-ticket: Audit/fix all uses of MixedIntegerLinearProgram in sage.combinat, sage.graphs).

We update the following methods in graph.py and bipartite_graph.py:

• degree_constrained_subgraph
• minimum_outdegree_orientation
• matching
• has_perfect_matching

Depends on #32197

CC: @mkoeppe @tscrim @dimpase

Component: graph theory

Author: David Coudert

Branch/Commit: b7e9915

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/32237

[dcoudert]

Branch: oublic/graphs/32237_graph_1

[dcoudert]

Dependencies: #32197

[dcoudert]

Last 10 new commits:

3dca4e9	MixedIntegerLinearProgram.get_values: If convert=True, convert real variables from float to base_ring
9ad3fa8	MixedIntegerLinearProgram.get_converted_values; subsumed by get_values
f62a777	src/sage/numerical/mip.pyx: Remove unused imports
cfd8c7b	trac #32197: remove another useless import
cf16293	MixedIntegerLinearProgram.get_values: Fix up for tolerance=None
5a74113	MixedIntegerLinearProgram._backend_variable_value: Add docstring
aa4eed5	MixedIntegerLinearProgram._backend_variable_value*: Add docstrings, examples
00b34aa	trac #32197: review commit
db83853	trac #32197: another review commit
231e9f8	trac #32237: graph part 1

[dcoudert]

Changed branch from oublic/graphs/32237_graph_1 to public/graphs/32237_graph_1

[dcoudert]

Commit: 231e9f8

[mkoeppe]

Reviewer: Matthias Koeppe

[mkoeppe]

comment:3

LGTM. Green patchbot => positive review

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

b7e9915

trac #32237: add paramter to method matching in bipartite_graph

[sagetrac-git]

Changed commit from 231e9f8 to b7e9915

[dcoudert]

comment:5

I forgot to modify method matching in bipartite_graph.py.

[mkoeppe]

comment:6

I've tested it locally

[vbraun]

Changed branch from public/graphs/32237_graph_1 to b7e9915