Hi Nicolas,
Perhaps I am going crazy, but I get:
----------------------------------------------------------------------
| Sage Version 4.1, Release Date: 2009-07-09 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
Loading Sage library. Current Mercurial branch is: combinat
sage: DynkinDiagram(["E",7,1])
O 2
|
|
O---O---O---O---O---O---O
0 1 3 4 5 6 7
E7~
sage: DynkinDiagram(["E",7])
O 2
|
|
O---O---O---O---O---O
1 3 4 5 6 7
E7
This is with all sage-combinat patches applied. What could be wrong?
Cheers,
Anne
>> The labeling of the Dynkin nodes for type E_7 in sage does not
>> seem consistent with the labeling of the affine nodes:
>> Should we fix this? It would make much more sense to attach node 2
>> in E_7 to node 4 instead of node 5.
>
> Err ???
>
> I could not reproduce that. On my machine, everything is fine:
>
> sage: DynkinDiagram(["E",7,1])
>
> O 2
> |
> |
> O---O---O---O---O---O---O
> 0 1 3 4 5 6 7
> E7~
> sage: DynkinDiagram(["E",7])
>
> O 2
> |
> |
> O---O---O---O---O---O
> 1 3 4 5 6 7
> E7
> sage: DynkinDiagram(["E",7,1]).edges()
>
> [(0, 1, 1), (1, 0, 1),
> (1, 3, 1), (2, 4, 1), (3, 1, 1), (3, 4, 1), (4, 2, 1), (4, 3, 1), (4, 5, 1),
> (5, 4, 1), (5, 6, 1), (6, 5, 1), (6, 7, 1), (7, 6, 1)]
> sage: DynkinDiagram(["E",7]).edges()
>
> [(1, 3, 1), (2, 4, 1), (3, 1, 1), (3, 4, 1), (4, 2, 1), (4, 3, 1), (4, 5, 1),
> (5, 4, 1), (5, 6, 1), (6, 5, 1), (6, 7, 1), (7, 6, 1)]
>
> Besides, there is an automatic test for this line 1168 of cartan_type.py::
>
> We check that :meth:`classical`, :meth:`.dynkin_diagram`, and
> :meth:`.special_node` are consistent::
>
> sage: for ct in CartanType.samples(affine = True):
> ... g1 = ct.classical().dynkin_diagram()
> ... g2 = ct.dynkin_diagram()
> ... g2.delete_vertex(ct.special_node())
> ... assert sorted(g1.vertices()) == sorted(g2.vertices())
> ... assert sorted(g1.edges()) == sorted(g2.edges())
>
> Cheers,
> Nicolas
>
>> sage: CartanType(['E',7]).dynkin_diagram()
>>
>> O 2
>> |
>> |
>> O---O---O---O---O---O
>> 1 3 4 5 6 7
>> E7
>>
>>
>> sage: CartanType(['E',7,1]).dynkin_diagram()
>>
>> O 2
>> |
>> |
>> O---O---O---O---O---O---O
>> 0 1 3 4 5 6 7
>> E7~
>>
>>
>> For type E_6 things are consistent:
>>
>>
>> sage: CartanType(['E',6]).dynkin_diagram()
>>
>> O 2
>> |
>> |
>> O---O---O---O---O
>> 1 3 4 5 6
>> E6
>> sage: CartanType(['E',6,1]).dynkin_diagram()
>>
>> O 0
>> |
>> |
>> O 2
>> |
>> |
>> O---O---O---O---O
>> 1 3 4 5 6
>> E6~
>>
>>
>> Anne
>>
>> Nicolas
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