#18627: Fix the weight lattice realization of a tensor product of crystals
-------------------------------------+-------------------------------------
Reporter: tscrim | Owner: sage-combinat
Type: defect | Status: needs_review
Priority: major | Milestone: sage-6.8
Component: combinatorics | Resolution:
Keywords: crystals, tensor | Merged in:
product | Reviewers: Ben Salisbury
Authors: Travis Scrimshaw | Work issues:
Report Upstream: N/A | Commit:
Branch: | aa5ba3452adb3489406eb202de1497c6f7d88ccb
public/crystals/common_parent_weights_tensors-18627| Stopgaps:
Dependencies: |
-------------------------------------+-------------------------------------
Changes (by bsalisbury1):
* reviewer: => Ben Salisbury
Comment:
Hi Travis,
I think the problem is still occurring is certain instances:
{{{
sage: R = RootSystem(['A',4,1])
sage: P = RootSystem(['A',4,1]).weight_lattice(extended=True)
sage: C = crystals.elementary.Component(R)
sage: La = P.fundamental_weights()
sage: TLa = crystals.elementary.T(R,La[0])
sage: Y = crystals.infinity.GeneralizedYoungWalls(4)
sage: T = crystals.TensorProduct(C,TLa,Y)
sage: mg = T(C[0],TLa[0],Y([]))
sage: mg.weight()
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
<ipython-input-26-8b7ee5a6cd87> in <module>()
----> 1 mg.weight()
/Users/Ben/sage-git/local/lib/python2.7/site-
packages/sage/combinat/crystals/tensor_product.pyc in weight(self)
1027 (-2, 1, 0, 1)
1028 """
-> 1029 return sum(self[i].weight() for i in range(len(self)))
1030
1031 def epsilon(self, i):
/Users/Ben/sage-git/local/lib/python2.7/site-
packages/sage/categories/additive_magmas.pyc in __add__(self, right)
414 from sage.structure.element import get_coercion_model
415 import operator
--> 416 return get_coercion_model().bin_op(self, right,
operator.add)
417
418 def __radd__(self, left):
/Users/Ben/sage-git/src/sage/structure/coerce.pyx in
sage.structure.coerce.CoercionModel_cache_maps.bin_op
(build/cythonized/sage/structure/coerce.c:9172)()
900
901
--> 902 cpdef bin_op(self, x, y, op):
903 """
904 Execute the operation op on x and y. It first looks for an
action
/Users/Ben/sage-git/src/sage/structure/coerce.pyx in
sage.structure.coerce.CoercionModel_cache_maps.bin_op
(build/cythonized/sage/structure/coerce.c:9059)()
1044 # We should really include the underlying error.
1045 # This causes so much headache.
-> 1046 raise TypeError, arith_error_message(x,y,op)
1047
1048 cpdef canonical_coercion(self, x, y):
TypeError: unsupported operand parent(s) for '+': 'Weight lattice of the
Root system of type ['A', 4, 1]' and 'Ambient space of the Root system of
type ['A', 4, 1]'
}}}
{{{
sage: C.weight_lattice_realization()
Weight lattice of the Root system of type ['A', 4, 1]
sage: TLa.weight_lattice_realization()
Ambient space of the Root system of type ['A', 4, 1]
sage: Y.weight_lattice_realization()
Weight lattice of the Root system of type ['A', 4, 1]
}}}
Is this particular error related to #18453 rather than this patch?
--
Ticket URL: <http://trac.sagemath.org/ticket/18627#comment:2>
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