#10441: Error creating an empty multi-edge (di)graph
----------------------------+-----------------------------------------------
Reporter: mhs | Owner: somebody
Type: defect | Status: new
Priority: major | Milestone: sage-4.6.1
Component: graph theory | Keywords: creating empty Graph, DiGraph,
multiple_edges=True
Author: MHS | Upstream: Not yet reported upstream; Will do
shortly.
Reviewer: somebody | Merged:
Work_issues: |
----------------------------+-----------------------------------------------
In SAGE 4.5.1 if you try to create an empty graph or digraph using the
multi-edge keyword the (di)graph created is a non-multi (di)graph.
Examples of the strange behaviour:
{{{
sage: G=Graph(multiple_edges=True)
sage: G
Graph on 0 vertices
}}}
{{{
sage: G=Graph([],multiple_edges=True)
sage: G
Graph on 0 vertices
}}}
{{{
sage: H=DiGraph(multiple_edges=True)
sage: H
Digraph on 0 vertices
}}}
{{{
sage: H=DiGraph([],multiple_edges=True)
sage: H
Digraph on 0 vertices
}}}
Nevertheless it works fine, i.e. produces a multi-graph/multi-digraph if
one uses an empty dictionary like in the following:
{{{
sage: G=Graph([],multiple_edges=True)
sage: G
Multi-graph on 0 vertices
}}}
{{{
sage: H=DiGraph({},multiple_edges=True)
sage: H
Multi-digraph on 0 vertices
}}}
After posting on sage-develop '''Strange behaviour of add_edges'''
[http://groups.google.com/group/sage-
devel/browse_thread/thread/69773eae8ba3cefc] I was asked to open a new
ticket...
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10441>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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