David Coudert

Results 13 issues of David Coudert

As discussed in #37977, we implement new iterators over the partitions of an integer to get iterators generating partitions in increasing/decreasing lexicographic orders with partitions in ascending/descending orders. We also...

s: needs review
c: combinatorics
v: large

As suggested in #37964, this PR add a method to enumerate cographs of order `n`. We add a new file that could collect all methods related to cographs (enumeration, random...

s: needs review
c: graph theory
v: large

Add a generator of random cographs. ### :memo: Checklist - [x] The title is concise and informative. - [x] The description explains in detail what this PR is about. -...

s: needs work
c: graph theory
v: small

This PR answers a query from https://ask.sagemath.org/question/78391/does-sage-have-a-function-to-determine-vertex-cuts/ It adds to (di)graphs a method to check if a set of vertices is a vertex cut of the (di)graph, that is if...

s: positive review
c: graph theory
v: moderate

Similarly to #38418, this PR adds a method to check whether a set of edges forms an edge cut of the (di)graph, that is if the removal of these edges...

s: needs review
c: graph theory

As suggested by @maxale in https://github.com/sagemath/sage/issues/38758#issuecomment-2391505302, we add a method to apply an orientation function to a graph and obtain the corresponding directed graph. ### :memo: Checklist - [x] The...

s: positive review
c: graph theory

This PR implements a non recursive version of method `gomory_hu_tree` for graphs. This fixes the max recursion depth error reported in https://ask.sagemath.org/question/79577/graphs-gomory-hu-tree-memory-blow-up-and-max-recursion-depth/. The memory consumption is seriously reduced. Without this...

s: needs review
c: graph theory

This PR fixes the issue with the output of method `acyclic_orientations` reported in https://ask.sagemath.org/question/79427/the-acyclic-orientations-function-behaves-unexpectedly/. Now the method outputs digraphs with the correct orientation of the arcs. ### :memo: Checklist -...

s: positive review
c: graph theory

As proposed in https://github.com/sagemath/sage/pull/39280#issuecomment-2577360470, we add a helper method `_scream_if_immutable` to (di)graphs. We then use it in several methods trying to modify the graph. ### :memo: Checklist - [x] The...

s: needs review
c: graph theory

Fixes #39930. Method `matching_polynomial` was failing for immutable graphs with loops. This is also related to discussions in #39177, i.e., ensure a correct behavior with immutable graphs. ### :memo: Checklist...

t: bug
s: needs review
c: graph theory