#15740: Better support for root systems which do not come from a Cartan type
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Reporter: tscrim | Owner: sage-combinat
Type: defect | Status: new
Priority: major | Milestone: sage-6.1
Component: combinatorics | Keywords:
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
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{{{
sage: d = DynkinDiagram()
sage: d.add_edge(1,2,3)
sage: d.add_edge(2,3)
sage: d.add_edge(3,4,3)
sage: d.cartan_matrix()
[ 2 -1 0 0]
[-3 2 -1 0]
[ 0 -1 2 -1]
[ 0 0 -3 2]
sage: Q = d.root_system().root_lattice()
sage: Q
Root lattice of the Root system of type Dynkin diagram of rank 4
sage: al = Q.simple_roots()
sage: al[1].reflection(al[2]) # Boom
}}}
This shouldn't be too hard to fix, just check if the Cartan type is `None`
(where applicable) and if so, call the corresponding Cartan matrix.
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Ticket URL: <http://trac.sagemath.org/ticket/15740>
Sage <http://www.sagemath.org>
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