Root system data for type B

class sage.combinat.root_system.type_B.AmbientSpace(root_system, base_ring)

Bases: sage.combinat.root_system.ambient_space.AmbientSpace

EXAMPLES:

sage: e = RootSystem(['A',3]).ambient_lattice()
sage: s = e.simple_reflections()

sage: L = RootSystem(['A',3]).coroot_lattice()
sage: e.has_coerce_map_from(L)
True
sage: e(L.simple_root(1))
(1, -1, 0, 0)
dimension()

EXAMPLES:

sage: e = RootSystem(['B',3]).ambient_space()
sage: e.dimension()
3
fundamental_weight(i)

EXAMPLES:

sage: RootSystem(['B',3]).ambient_space().fundamental_weights()
Finite family {1: (1, 0, 0), 2: (1, 1, 0), 3: (1/2, 1/2, 1/2)}
negative_roots()

EXAMPLES:

sage: RootSystem(['B',3]).ambient_space().negative_roots()
[(-1, 1, 0),
 (-1, -1, 0),
 (-1, 0, 1),
 (-1, 0, -1),
 (0, -1, 1),
 (0, -1, -1),
 (-1, 0, 0),
 (0, -1, 0),
 (0, 0, -1)]
positive_roots()

EXAMPLES:

sage: RootSystem(['B',3]).ambient_space().positive_roots()
[(1, -1, 0),
 (1, 1, 0),
 (1, 0, -1),
 (1, 0, 1),
 (0, 1, -1),
 (0, 1, 1),
 (1, 0, 0),
 (0, 1, 0),
 (0, 0, 1)]
root(i, j)

Note that indexing starts at 0.

EXAMPLES:

sage: e = RootSystem(['B',3]).ambient_space()
sage: e.root(0,1)
(1, -1, 0)
simple_root(i)

EXAMPLES:

sage: e = RootSystem(['B',4]).ambient_space()
sage: e.simple_roots()
Finite family {1: (1, -1, 0, 0), 2: (0, 1, -1, 0), 3: (0, 0, 1, -1), 4: (0, 0, 0, 1)}
sage: e.positive_roots()
[(1, -1, 0, 0),
(1, 1, 0, 0),
(1, 0, -1, 0),
(1, 0, 1, 0),
(1, 0, 0, -1),
(1, 0, 0, 1),
(0, 1, -1, 0),
(0, 1, 1, 0),
(0, 1, 0, -1),
(0, 1, 0, 1),
(0, 0, 1, -1),
(0, 0, 1, 1),
(1, 0, 0, 0),
(0, 1, 0, 0),
(0, 0, 1, 0),
(0, 0, 0, 1)]
sage: e.fundamental_weights()
Finite family {1: (1, 0, 0, 0), 2: (1, 1, 0, 0), 3: (1, 1, 1, 0), 4: (1/2, 1/2, 1/2, 1/2)}
class sage.combinat.root_system.type_B.CartanType(n)

Bases: sage.combinat.root_system.cartan_type.CartanType_standard_finite, sage.combinat.root_system.cartan_type.CartanType_simple, sage.combinat.root_system.cartan_type.CartanType_crystallographic

EXAMPLES:

sage: ct = CartanType(['B',4])
sage: ct
['B', 4]
sage: ct._repr_(compact = True)
'B4'

sage: ct.is_irreducible()
True
sage: ct.is_finite()
True
sage: ct.is_affine()
False
sage: ct.is_crystallographic()
True
sage: ct.is_simply_laced()
False
sage: ct.affine()
['B', 4, 1]
sage: ct.dual()
['C', 4]

sage: ct = CartanType(['B',1])
sage: ct.is_simply_laced()
True
sage: ct.affine()
['B', 1, 1]

TESTS:

sage: TestSuite(ct).run()
AmbientSpace

alias of AmbientSpace

ascii_art(label=<function <lambda> at 0x7fb316ba72a8>)

Return an ascii art representation of the Dynkin diagram.

EXAMPLES:

sage: print CartanType(['B',1]).ascii_art()
O
1
sage: print CartanType(['B',2]).ascii_art()
O=>=O
1   2
sage: print CartanType(['B',5]).ascii_art(label = lambda x: x+2)
O---O---O---O=>=O
3   4   5   6   7
coxeter_number()

Return the Coxeter number associated with self.

EXAMPLES:

sage: CartanType(['B',4]).coxeter_number()
8
dual()

Types B and C are in duality:

EXAMPLES:

sage: CartanType(["C", 3]).dual()
['B', 3]
dual_coxeter_number()

Return the dual Coxeter number associated with self.

EXAMPLES:

sage: CartanType(['B',4]).dual_coxeter_number()
7
dynkin_diagram()

Returns a Dynkin diagram for type B.

EXAMPLES:

sage: b = CartanType(['B',3]).dynkin_diagram()
sage: b
O---O=>=O
1   2   3
B3
sage: sorted(b.edges())
[(1, 2, 1), (2, 1, 1), (2, 3, 2), (3, 2, 1)]

sage: b = CartanType(['B',1]).dynkin_diagram()
sage: b
O
1
B1
sage: sorted(b.edges())
[]

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