From 74e505b8b769247b91482298aeebfa19fc64995b Mon Sep 17 00:00:00 2001 From: Jonathan Kliem Date: Mon, 4 Oct 2021 11:59:22 +0200 Subject: [PATCH] edge disjoint spanning tree not as fast as claimed, see #32169 --- src/sage/graphs/generic_graph.py | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/src/sage/graphs/generic_graph.py b/src/sage/graphs/generic_graph.py index 983f9c9bdc9..be2e927f40e 100644 --- a/src/sage/graphs/generic_graph.py +++ b/src/sage/graphs/generic_graph.py @@ -6262,7 +6262,7 @@ def edge_disjoint_spanning_trees(self, k, root=None, solver=None, verbose=0): By Edmond's theorem, a graph which is `k`-connected always has `k` edge-disjoint arborescences, regardless of the root we pick:: - sage: g = digraphs.RandomDirectedGNP(11, .3) # reduced from 30 to 11, cf. #32169 + sage: g = digraphs.RandomDirectedGNP(11, .3) # reduced from 30 to 11, cf. #32169 sage: k = Integer(g.edge_connectivity()) sage: while not k: ....: g = digraphs.RandomDirectedGNP(11, .3) @@ -6275,9 +6275,9 @@ def edge_disjoint_spanning_trees(self, k, root=None, solver=None, verbose=0): In the undirected case, we can only ensure half of it:: - sage: g = graphs.RandomGNP(30, .3) - sage: while not g.is_connected(): - ....: g = graphs.RandomGNP(30, .3) + sage: g = graphs.RandomGNP(14, .3) # reduced from 30 to 14, see #32169 + sage: while not g.is_biconnected(): + ....: g = graphs.RandomGNP(14, .3) sage: k = Integer(g.edge_connectivity()) // 2 sage: trees = g.edge_disjoint_spanning_trees(k) sage: all(t.is_tree() for t in trees)