Bases: sage.categories.category_singleton.Category_singleton
The category of crystals
See sage.combinat.crystals for an introduction to crystals.
EXAMPLES:
sage: C = Crystals()
sage: C
Category of crystals
sage: C.super_categories()
[Category of... enumerated sets]
sage: C.example()
Highest weight crystal of type A_3 of highest weight omega_1
Parents in this category should implement the following methods:
- either a method cartan_type or an attribute _cartan_type
- module_generators: a list (or container) of distinct elements which generate the crystal using
Furthermore, their elements should implement the following methods:
- x.e(i) (returning
)
- x.f(i) (returning
)
EXAMPLES:
sage: from sage.misc.abstract_method import abstract_methods_of_class
sage: abstract_methods_of_class(Crystals().element_class)
{'required': ['e', 'f'], 'optional': []}
TESTS:
sage: TestSuite(C).run()
sage: B = Crystals().example()
sage: TestSuite(B).run(verbose = True)
running ._test_an_element() . . . pass
running ._test_category() . . . pass
running ._test_elements() . . .
Running the test suite of self.an_element()
running ._test_category() . . . pass
running ._test_eq() . . . pass
running ._test_not_implemented_methods() . . . pass
running ._test_pickling() . . . pass
running ._test_stembridge_local_axioms() . . . pass
pass
running ._test_elements_eq() . . . pass
running ._test_enumerated_set_contains() . . . pass
running ._test_enumerated_set_iter_cardinality() . . . pass
running ._test_enumerated_set_iter_list() . . . pass
running ._test_eq() . . . pass
running ._test_fast_iter() . . . pass
running ._test_not_implemented_methods() . . . pass
running ._test_pickling() . . . pass
running ._test_some_elements() . . . pass
running ._test_stembridge_local_axioms() . . . pass
EXAMPLES:
sage: C = CrystalOfLetters(['A',5])
sage: C(0).Epsilon()
(0, 0, 0, 0, 0, 0)
sage: C(1).Epsilon()
(0, 0, 0, 0, 0, 0)
sage: C(2).Epsilon()
(1, 0, 0, 0, 0, 0)
EXAMPLES:
sage: C = CrystalOfLetters(['A',5])
sage: C(0).Phi()
(0, 0, 0, 0, 0, 0)
sage: C(1).Phi()
(1, 0, 0, 0, 0, 0)
sage: C(2).Phi()
(1, 1, 0, 0, 0, 0)
Returns the cartan type associated to self
EXAMPLES:
sage: C = CrystalOfLetters(['A', 5])
sage: C(1).cartan_type()
['A', 5]
Returns the Demazure operator applied on self.
INPUT:
OUTPUT:
Let .
If , this returns the sum of the elements obtained
from self by application of
for
.
If , this returns the opposite of the sum of the
elements obtained by application of
for
.
REFERENCES:
[L1995] Peter Littelmann, Crystal graphs and Young tableaux, J. Algebra 175 (1995), no. 1, 65–87.
[K1993] Masaki Kashiwara, The crystal base and Littelmann’s refined Demazure character formula, Duke Math. J. 71 (1993), no. 3, 839–858.
EXAMPLES:
sage: T = CrystalOfTableaux(['A',2], shape=[2,1])
sage: t=T(rows=[[1,2],[2]])
sage: t.demazure_operator_simple(2)
B[[[1, 2], [2]]] + B[[[1, 3], [2]]] + B[[[1, 3], [3]]]
sage: t.demazure_operator_simple(2).parent()
Free module generated by The crystal of tableaux of type ['A', 2] and shape(s) [[2, 1]] over Integer Ring
sage: t.demazure_operator_simple(1)
0
sage: K = KirillovReshetikhinCrystal(['A',2,1],2,1)
sage: t = K(rows=[[3],[2]])
sage: t.demazure_operator_simple(0)
B[[[2, 3]]] + B[[[1, 2]]]
TESTS:
sage: K = KirillovReshetikhinCrystal(['A',2,1],1,1)
sage: x = K.an_element(); x
[[1]]
sage: x.demazure_operator_simple(0)
0
sage: x.demazure_operator_simple(0, ring = QQ).parent()
Free module generated by Kirillov-Reshetikhin crystal of type ['A', 2, 1] with (r,s)=(1,1) over Rational Field
Returns if it exists or None otherwise.
This method should be implemented by the element class of the crystal.
EXAMPLES:
sage: C = Crystals().example(5)
sage: x = C[2]; x
3
sage: x.e(1), x.e(2), x.e(3)
(None, 2, None)
Applies to self for
EXAMPLES:
sage: C = CrystalOfLetters(['A',3])
sage: b = C(3)
sage: b.e_string([2,1])
1
sage: b.e_string([1,2])
EXAMPLES:
sage: C = CrystalOfLetters(['A',5])
sage: C(1).epsilon(1)
0
sage: C(2).epsilon(1)
1
Returns if it exists or None otherwise.
This method should be implemented by the element class of the crystal.
EXAMPLES:
sage: C = Crystals().example(5)
sage: x = C[1]; x
2
sage: x.f(1), x.f(2), x.f(3)
(None, 3, None)
Applies to self for
EXAMPLES:
sage: C = CrystalOfLetters(['A',3])
sage: b = C(1)
sage: b.f_string([1,2])
3
sage: b.f_string([2,1])
EXAMPLES:
sage: C = CrystalOfLetters(['A',5])
sage: C(1).index_set()
[1, 2, 3, 4, 5]
Returns True if self is a highest weight.
Specifying the option index_set to be a subset of the
index set of the underlying crystal, finds all highest
weight vectors for arrows in
.
EXAMPLES:
sage: C = CrystalOfLetters(['A',5])
sage: C(1).is_highest_weight()
True
sage: C(2).is_highest_weight()
False
sage: C(2).is_highest_weight(index_set = [2,3,4,5])
True
Returns True if self is a lowest weight.
Specifying the option index_set to be a subset of the
index set of the underlying crystal, finds all lowest
weight vectors for arrows in
.
EXAMPLES:
sage: C = CrystalOfLetters(['A',5])
sage: C(1).is_lowest_weight()
False
sage: C(6).is_lowest_weight()
True
sage: C(4).is_lowest_weight(index_set = [1,3])
True
EXAMPLES:
sage: C = CrystalOfLetters(['A',5])
sage: C(1).phi(1)
1
sage: C(2).phi(1)
0
Returns of self. There are sometimes
better implementations using the weight for this. It is used
for reflections along a string.
EXAMPLES:
sage: C = CrystalOfLetters(['A',5])
sage: C(1).phi_minus_epsilon(1)
1
Returns the reflection of self along its -string
EXAMPLES:
sage: C = CrystalOfTableaux(['A',2], shape=[2,1])
sage: b=C(rows=[[1,1],[3]])
sage: b.s(1)
[[2, 2], [3]]
sage: b=C(rows=[[1,2],[3]])
sage: b.s(2)
[[1, 2], [3]]
sage: T=CrystalOfTableaux(['A',2],shape=[4])
sage: t=T(rows=[[1,2,2,2]])
sage: t.s(1)
[[1, 1, 1, 2]]
The -depth of a crystal node
is -x.epsilon(i).
This function returns the difference in the
-depth of
and x.f(i),
where
and
are in the index set of the underlying crystal.
This function is useful for checking the Stembridge local axioms for crystal bases.
EXAMPLES:
sage: T = CrystalOfTableaux(['A',2], shape=[2,1])
sage: t=T(rows=[[1,1],[2]])
sage: t.stembridgeDel_depth(1,2)
0
sage: s=T(rows=[[1,3],[3]])
sage: s.stembridgeDel_depth(1,2)
-1
The -rise of a crystal node
is x.phi(i).
This function returns the difference in the
-rise of
and x.f(i),
where
and
are in the index set of the underlying crystal.
This function is useful for checking the Stembridge local axioms for crystal bases.
EXAMPLES:
sage: T = CrystalOfTableaux(['A',2], shape=[2,1])
sage: t=T(rows=[[1,1],[2]])
sage: t.stembridgeDel_rise(1,2)
-1
sage: s=T(rows=[[1,3],[3]])
sage: s.stembridgeDel_rise(1,2)
0
The -depth of a crystal node
is -x.epsilon(i).
This function returns the difference in the
-depth of
and x.e(i),
where
and
are in the index set of the underlying crystal.
This function is useful for checking the Stembridge local axioms for crystal bases.
EXAMPLES:
sage: T = CrystalOfTableaux(['A',2], shape=[2,1])
sage: t=T(rows=[[1,2],[2]])
sage: t.stembridgeDelta_depth(1,2)
0
sage: s=T(rows=[[2,3],[3]])
sage: s.stembridgeDelta_depth(1,2)
-1
The -rise of a crystal node
is x.phi(i).
This function returns the difference in the -rise of
and x.e(i),
where
and
are in the index set of the underlying crystal.
This function is useful for checking the Stembridge local axioms for crystal bases.
EXAMPLES:
sage: T = CrystalOfTableaux(['A',2], shape=[2,1])
sage: t=T(rows=[[1,2],[2]])
sage: t.stembridgeDelta_rise(1,2)
-1
sage: s=T(rows=[[2,3],[3]])
sage: s.stembridgeDelta_rise(1,2)
0
Let be the Cartan matrix of the crystal,
a crystal element,
and let
and
be in the index set of the crystal.
Further, set
b=stembridgeDelta_depth(x,i,j), and
c=stembridgeDelta_rise(x,i,j)).
If x.e(i) is non-empty, this function returns the triple
; otherwise it returns None.
By the Stembridge local characterization of crystal bases, one should have
.
EXAMPLES:
sage: T = CrystalOfTableaux(['A',2], shape=[2,1])
sage: t=T(rows=[[1,1],[2]])
sage: t.stembridgeTriple(1,2)
sage: s=T(rows=[[1,2],[2]])
sage: s.stembridgeTriple(1,2)
(-1, 0, -1)
sage: T = CrystalOfTableaux(['B',2], shape=[2,1])
sage: t=T(rows=[[1,2],[2]])
sage: t.stembridgeTriple(1,2)
(-2, 0, -2)
sage: s=T(rows=[[-1,-1],[0]])
sage: s.stembridgeTriple(1,2)
(-2, -2, 0)
sage: u=T(rows=[[0,2],[1]])
sage: u.stembridgeTriple(1,2)
(-2, -1, -1)
Yields the highest weight element and a list
such that
, where
are
elements in
. By default the index set is assumed to be
the full index set of self.
EXAMPLES:
sage: T = CrystalOfTableaux(['A',3], shape = [1])
sage: t = T(rows = [[3]])
sage: t.to_highest_weight()
[[[1]], [2, 1]]
sage: T = CrystalOfTableaux(['A',3], shape = [2,1])
sage: t = T(rows = [[1,2],[4]])
sage: t.to_highest_weight()
[[[1, 1], [2]], [1, 3, 2]]
sage: t.to_highest_weight(index_set = [3])
[[[1, 2], [3]], [3]]
sage: K = KirillovReshetikhinCrystal(['A',3,1],2,1)
sage: t = K(rows=[[2],[3]]); t.to_highest_weight(index_set=[1])
[[[1], [3]], [1]]
sage: t.to_highest_weight()
Traceback (most recent call last):
...
ValueError: This is not a highest weight crystals!
Yields the lowest weight element and a list
such that
, where
are
elements in
. By default the index set is assumed to be
the full index set of self.
EXAMPLES:
sage: T = CrystalOfTableaux(['A',3], shape = [1])
sage: t = T(rows = [[3]])
sage: t.to_lowest_weight()
[[[4]], [3]]
sage: T = CrystalOfTableaux(['A',3], shape = [2,1])
sage: t = T(rows = [[1,2],[4]])
sage: t.to_lowest_weight()
[[[3, 4], [4]], [1, 2, 2, 3]]
sage: t.to_lowest_weight(index_set = [3])
[[[1, 2], [4]], []]
sage: K = KirillovReshetikhinCrystal(['A',3,1],2,1)
sage: t = K.module_generator(); t
[[1], [2]]
sage: t.to_lowest_weight(index_set=[1,2,3])
[[[3], [4]], [2, 1, 3, 2]]
sage: t.to_lowest_weight()
Traceback (most recent call last):
...
ValueError: This is not a highest weight crystals!
Returns the weight of this crystal element
EXAMPLES:
sage: C = CrystalOfLetters(['A',5])
sage: C(1).weight()
(1, 0, 0, 0, 0, 0)
Returns the fundamental weights in the weight lattice realization for the root system associated with the crystal
EXAMPLES:
sage: C = CrystalOfLetters(['A', 5])
sage: C.Lambda()
Finite family {1: (1, 0, 0, 0, 0, 0), 2: (1, 1, 0, 0, 0, 0), 3: (1, 1, 1, 0, 0, 0), 4: (1, 1, 1, 1, 0, 0), 5: (1, 1, 1, 1, 1, 0)}
Returns an element of self
sage: C = CrystalOfLetters([‘A’, 5]) sage: C.an_element() 1
Returns the Cartan type of the crystal
Constructs a morphism from the crystal self to another crystal.
The input can either be a function of a (sub)set of elements of self to
element in another crystal or a dictionary between certain elements.
Usually one would map highest weight elements or crystal generators to each
other using g.
Specifying index_set gives the opportunity to define the morphism as
-crystals
where
index_set. If index_set is not specified, the index set of self is used.
It is also possible to define twisted-morphisms by specifying an automorphism on the
nodes in te Dynkin diagram (or the index_set).
The option direction and direction_image indicate whether to use
or
in
self or the image crystal to construct the morphism, depending on whether the direction
is set to ‘down’ or ‘up’.
It is also possible to set a similarity_factor. This should be a dictionary between
the elements in the index set and positive integers. The crystal operator
then gets
mapped to
where
similarity_factor[i].
Setting similarity_factor_domain to a dictionary between the index set and positive integers
has the effect that
gets mapped to
where
similarity_factor_domain[i].
Finally, it is possible to set the option
. This calculates an isomorphism
for cyclic crystals (for example finite affine crystals). In this case the input function
is supposed to be given as a dictionary.
EXAMPLES:
sage: C2 = CrystalOfLetters(['A',2])
sage: C3 = CrystalOfLetters(['A',3])
sage: g = {C2.module_generators[0] : C3.module_generators[0]}
sage: g_full = C2.crystal_morphism(g)
sage: g_full(C2(1))
1
sage: g_full(C2(2))
2
sage: g = {C2(1) : C2(3)}
sage: g_full = C2.crystal_morphism(g, automorphism = lambda i : 3-i, direction_image = 'up')
sage: [g_full(b) for b in C2]
[3, 2, 1]
sage: T = CrystalOfTableaux(['A',2], shape = [2])
sage: g = {C2(1) : T(rows=[[1,1]])}
sage: g_full = C2.crystal_morphism(g, similarity_factor = {1:2, 2:2})
sage: [g_full(b) for b in C2]
[[[1, 1]], [[2, 2]], [[3, 3]]]
sage: g = {T(rows=[[1,1]]) : C2(1)}
sage: g_full = T.crystal_morphism(g, similarity_factor_domain = {1:2, 2:2})
sage: g_full(T(rows=[[2,2]]))
2
sage: B1=KirillovReshetikhinCrystal(['A',2,1],1,1)
sage: B2=KirillovReshetikhinCrystal(['A',2,1],1,2)
sage: T=TensorProductOfCrystals(B1,B2)
sage: T1=TensorProductOfCrystals(B2,B1)
sage: La = T.weight_lattice_realization().fundamental_weights()
sage: t = [b for b in T if b.weight() == -3*La[0] + 3*La[1]][0]
sage: t1 = [b for b in T1 if b.weight() == -3*La[0] + 3*La[1]][0]
sage: g={t:t1}
sage: f=T.crystal_morphism(g,acyclic = False)
sage: [[b,f(b)] for b in T]
[[[[[1]], [[1, 1]]], [[[1, 1]], [[1]]]],
[[[[1]], [[1, 2]]], [[[1, 1]], [[2]]]],
[[[[1]], [[2, 2]]], [[[1, 2]], [[2]]]],
[[[[1]], [[1, 3]]], [[[1, 1]], [[3]]]],
[[[[1]], [[2, 3]]], [[[1, 2]], [[3]]]],
[[[[1]], [[3, 3]]], [[[1, 3]], [[3]]]],
[[[[2]], [[1, 1]]], [[[1, 2]], [[1]]]],
[[[[2]], [[1, 2]]], [[[2, 2]], [[1]]]],
[[[[2]], [[2, 2]]], [[[2, 2]], [[2]]]],
[[[[2]], [[1, 3]]], [[[2, 3]], [[1]]]],
[[[[2]], [[2, 3]]], [[[2, 2]], [[3]]]],
[[[[2]], [[3, 3]]], [[[2, 3]], [[3]]]],
[[[[3]], [[1, 1]]], [[[1, 3]], [[1]]]],
[[[[3]], [[1, 2]]], [[[1, 3]], [[2]]]],
[[[[3]], [[2, 2]]], [[[2, 3]], [[2]]]],
[[[[3]], [[1, 3]]], [[[3, 3]], [[1]]]],
[[[[3]], [[2, 3]]], [[[3, 3]], [[2]]]],
[[[[3]], [[3, 3]]], [[[3, 3]], [[3]]]]]
Returns the application of Demazure operators for
from reduced_word on element.
INPUT:
OUTPUT:
EXAMPLES:
sage: T = CrystalOfTableaux(['A',2], shape=[2,1])
sage: C = CombinatorialFreeModule(QQ,T)
sage: t = T.highest_weight_vector()
sage: b = 2*C(t)
sage: T.demazure_operator(b,[1,2,1])
2*B[[[1, 1], [2]]] + 2*B[[[1, 2], [2]]] + 2*B[[[1, 3], [2]]] + 2*B[[[1, 1], [3]]]
+ 2*B[[[1, 2], [3]]] + 2*B[[[1, 3], [3]]] + 2*B[[[2, 2], [3]]] + 2*B[[[2, 3], [3]]]
The Demazure operator is idempotent:
sage: T = CrystalOfTableaux("A1",shape=[4])
sage: C = CombinatorialFreeModule(QQ,T)
sage: b = C(T.module_generators[0]); b
B[[[1, 1, 1, 1]]]
sage: e = T.demazure_operator(b,[1]); e
B[[[1, 1, 1, 1]]] + B[[[1, 1, 1, 2]]] + B[[[1, 1, 2, 2]]] + B[[[1, 2, 2, 2]]] + B[[[2, 2, 2, 2]]]
sage: e == T.demazure_operator(e,[1])
True
sage: all(T.demazure_operator(T.demazure_operator(C(t),[1]),[1]) == T.demazure_operator(C(t),[1]) for t in T)
True
Returns the DiGraph associated to self.
INPUT:
EXAMPLES:
sage: C = Crystals().example(5)
sage: C.digraph()
Digraph on 6 vertices
The edges of the crystal graph are by default colored using blue for edge 1, red for edge 2, and green for edge 3:
sage: C = Crystals().example(3)
sage: G = C.digraph()
sage: view(G, pdflatex=True, tightpage=True) #optional - dot2tex graphviz
One may also overwrite the colors:
sage: C = Crystals().example(3)
sage: G = C.digraph()
sage: G.set_latex_options(color_by_label = {1:"red", 2:"purple", 3:"blue"})
sage: view(G, pdflatex=True, tightpage=True) #optional - dot2tex graphviz
Or one may add colors to yet unspecified edges:
sage: C = Crystals().example(4)
sage: G = C.digraph()
sage: C.cartan_type()._index_set_coloring[4]="purple"
sage: view(G, pdflatex=True, tightpage=True) #optional - dot2tex graphviz
Here is an example of how to take the top part up to a given depth of an infinite dimensional crystal:
sage: C = CartanType(['C',2,1])
sage: La = C.root_system().weight_lattice().fundamental_weights()
sage: T = HighestWeightCrystal(La[0])
sage: S = T.subcrystal(max_depth=3)
sage: G = T.digraph(subset=S); G
Digraph on 5 vertices
sage: G.vertices()
[(1/2*Lambda[0] + Lambda[1] - Lambda[2] - 1/2*delta, -1/2*Lambda[0] + Lambda[1] - 1/2*delta),
(-Lambda[0] + 2*Lambda[1] - delta,), (Lambda[0] - 2*Lambda[1] + 2*Lambda[2] - delta,),
(1/2*Lambda[0] - Lambda[1] + Lambda[2] - 1/2*delta, -1/2*Lambda[0] + Lambda[1] - 1/2*delta), (Lambda[0],)]
Here is a way to construct a picture of a Demazure crystal using the subset option:
sage: B = CrystalOfTableaux(['A',2], shape=[2,1])
sage: C = CombinatorialFreeModule(QQ,B)
sage: t = B.highest_weight_vector()
sage: b = C(t)
sage: D = B.demazure_operator(b,[2,1]); D
B[[[1, 1], [2]]] + B[[[1, 2], [2]]] + B[[[1, 3], [2]]] + B[[[1, 1], [3]]] + B[[[1, 3], [3]]]
sage: G = B.digraph(subset=D.support())
sage: G.vertices()
[[[1, 1], [2]], [[1, 2], [2]], [[1, 3], [2]], [[1, 1], [3]], [[1, 3], [3]]]
sage: view(G, pdflatex=True, tightpage=True) #optional - dot2tex graphviz
We can also choose to display particular arrows using the index_set option:
sage: C = KirillovReshetikhinCrystal(['D',4,1], 2, 1)
sage: G = C.digraph(index_set=[1,3])
sage: len(G.edges())
20
sage: view(G, pdflatex=True, tightpage=True) #optional - dot2tex graphviz
TODO: add more tests
Returns a dot_tex string representation of self.
EXAMPLES:
sage: C = CrystalOfLetters(['A',2])
sage: C.dot_tex()
'digraph G { \n node [ shape=plaintext ];\n N_0 [ label = " ", texlbl = "$1$" ];\n N_1 [ label = " ", texlbl = "$2$" ];\n N_2 [ label = " ", texlbl = "$3$" ];\n N_0 -> N_1 [ label = " ", texlbl = "1" ];\n N_1 -> N_2 [ label = " ", texlbl = "2" ];\n}'
Returns the index set of the Dynkin diagram underlying the crystal
Returns the crystal graph as a latex string. This can be exported to a file with self.latex_file(‘filename’).
EXAMPLES:
sage: T = CrystalOfTableaux(['A',2],shape=[1])
sage: T._latex_() #optional - dot2tex
'...tikzpicture...'
sage: view(T, pdflatex = True, tightpage = True) #optional - dot2tex graphviz
One can for example also color the edges using the following options:
sage: T = CrystalOfTableaux(['A',2],shape=[1])
sage: T._latex_(color_by_label = {0:"black", 1:"red", 2:"blue"}) #optional - dot2tex graphviz
'...tikzpicture...'
Exports a file, suitable for pdflatex, to ‘filename’. This requires a proper installation of dot2tex in sage-python. For more information see the documentation for self.latex().
EXAMPLES:
sage: C = CrystalOfLetters(['A', 5])
sage: C.latex_file('/tmp/test.tex') #optional - dot2tex
Use C.metapost(“filename.mp”,[options]), where options can be:
thicklines = True (for thicker edges) labels = False (to suppress labeling of the vertices) scaling_factor=value, where value is a floating point number, 1.0 by default. Increasing or decreasing the scaling factor changes the size of the image. tallness=1.0. Increasing makes the image taller without increasing the width.
Root operators e(1) or f(1) move along red lines, e(2) or f(2) along green. The highest weight is in the lower left. Vertices with the same weight are kept close together. The concise labels on the nodes are strings introduced by Berenstein and Zelevinsky and Littelmann; see Littelmann’s paper Cones, Crystals, Patterns, sections 5 and 6.
For Cartan types B2 or C2, the pattern has the form
a2 a3 a4 a1
where c*a2 = a3 = 2*a4 =0 and a1=0, with c=2 for B2, c=1 for C2. Applying e(2) a1 times, e(1) a2 times, e(2) a3 times, e(1) a4 times returns to the highest weight. (Observe that Littelmann writes the roots in opposite of the usual order, so our e(1) is his e(2) for these Cartan types.) For type A2, the pattern has the form
a3 a2 a1
where applying e(1) a1 times, e(2) a2 times then e(3) a1 times returns to the highest weight. These data determine the vertex and may be translated into a Gelfand-Tsetlin pattern or tableau.
EXAMPLES:
sage: C = CrystalOfLetters(['A', 2])
sage: C.metapost('/tmp/test.mp') #optional
sage: C = CrystalOfLetters(['A', 5])
sage: C.metapost('/tmp/test.mp')
Traceback (most recent call last):
...
NotImplementedError
Returns the plot of self as a directed graph.
EXAMPLES:
sage: C = CrystalOfLetters(['A', 5])
sage: show_default(False) #do not show the plot by default
sage: C.plot()
Graphics object consisting of 17 graphics primitives
Returns the 3-dimensional plot of self as a directed graph.
EXAMPLES:
sage: C = KirillovReshetikhinCrystal(['A',3,1],2,1)
sage: C.plot3d()
Graphics3d Object
Construct the subcrystal from generators using and
for all
in index_set.
INPUT:
EXAMPLES:
sage: C = KirillovReshetikhinCrystal(['A',3,1], 1, 2)
sage: S = list(C.subcrystal(index_set=[1,2])); S
[[[1, 1]], [[1, 2]], [[1, 3]], [[2, 2]], [[2, 3]], [[3, 3]]]
sage: C.cardinality()
10
sage: len(S)
6
sage: list(C.subcrystal(index_set=[1,3], generators=[C(1,4)]))
[[[1, 4]], [[2, 4]], [[1, 3]], [[2, 3]]]
sage: list(C.subcrystal(index_set=[1,3], generators=[C(1,4)], max_depth=1))
[[[1, 4]], [[2, 4]], [[1, 3]]]
sage: list(C.subcrystal(index_set=[1,3], generators=[C(1,4)], direction='upper'))
[[[1, 4]], [[1, 3]]]
sage: list(C.subcrystal(index_set=[1,3], generators=[C(1,4)], direction='lower'))
[[[1, 4]], [[2, 4]]]
Returns the weight lattice realization used to express weights.
This default implementation uses the ambient space of the root system for (non relabelled) finite types and the weight lattice otherwise. This is a legacy from when ambient spaces were partially implemented, and may be changed in the future.
EXAMPLES:
sage: C = CrystalOfLetters(['A', 5])
sage: C.weight_lattice_realization()
Ambient space of the Root system of type ['A', 5]
sage: K = KirillovReshetikhinCrystal(['A',2,1], 1, 1)
sage: K.weight_lattice_realization()
Weight lattice of the Root system of type ['A', 2, 1]
Returns an example of a crystal, as per Category.example().
INPUT:
- ``choice`` -- str [default: 'highwt']. Can be either 'highwt'
for the highest weight crystal of type A, or 'naive' for an
example of a broken crystal.
- ``**kwds`` -- keyword arguments passed onto the constructor for the
chosen crystal.
EXAMPLES:
sage: Crystals().example(choice='highwt', n=5)
Highest weight crystal of type A_5 of highest weight omega_1
sage: Crystals().example(choice='naive')
A broken crystal, defined by digraph, of dimension five.
EXAMPLES:
sage: Crystals().super_categories()
[Category of enumerated sets]