Opened 10 years ago

Last modified 7 years ago

#12387 new defect

Everything is not well with dense graph backends

Reported by: ncohen Owned by: jason, ncohen, rlm
Priority: major Milestone: sage-6.4
Component: graph theory Keywords:
Cc: brunellus, rlm Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

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Description

We discovered in #12318 that some functions of sage/geometry/polyhedra and sage/geometry/triangulation/point_configuration.py return wrong results if Graph(sparse = True) is replaced by Graph(sparse = False)

Change History (7)

comment:1 Changed 10 years ago by brunellus

The dense graph code doesn't support edge labeling, but the code in point_configuration.py rely on this. Maybe it is a mistake that dense_graph doesn't crash and burn whenever someone call add_edge(u, v, nonNone) -- but it is consistent with cases like

sage: G=Graph(multiedges=False)
sage: G.add_edge(0,1)
sage: G.add_edge(0,1)
sage: G.edges()
[(0, 1, None)]

comment:2 Changed 10 years ago by vbraun

I wrote the code for polyhedra. It is definitely a bug if the graph silently gives the wrong answer just because some backend doesn't support edge labels.

comment:3 Changed 10 years ago by brunellus

I started #12540 for this discussion.

I will investigate further if the lack of edge labels is the only source of the wrong results we spotted in #12318.

comment:4 Changed 8 years ago by jdemeyer

  • Milestone changed from sage-5.11 to sage-5.12

comment:5 Changed 8 years ago by vbraun_spam

  • Milestone changed from sage-6.1 to sage-6.2

comment:6 Changed 8 years ago by vbraun_spam

  • Milestone changed from sage-6.2 to sage-6.3

comment:7 Changed 7 years ago by vbraun_spam

  • Milestone changed from sage-6.3 to sage-6.4
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