`TypeError` on compressing a Coset Table generated by coset table method #11449

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gxyd opened this Issue Jul 30, 2016 · 0 comments

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gxyd commented Jul 30, 2016
>>> from sympy import *
>>> from sympy.combinatorics.free_group import free_group
>>> from sympy.combinatorics.fp_groups import FpGroup, coset_enumeration_c
>>> F, r, s, t = free_group("r, s, t")
>>> E1 = FpGroup(F, [t**-1*r*t*r**-2, r**-1*s*r*s**-2, s**-1*t*s*t**-2])
>>> C1 = coset_enumeration_c(E1, [])
>>> C1.compress()
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-10-fdff318db95f> in <module>()
----> 1 C1.compress()

/home/gaurav/Public/sympy/sympy/combinatorics/fp_groups.py in compress(self)
    572                     beta = self.table[alpha][A_dict[x]]
    573                     self.table[gamma][A_dict[x]] = beta
--> 574                     self.table[beta][A_dict_inv[x]] == gamma
    575         # all the cosets in the table are live cosets
    576         self.p = list(range(gamma + 1))

TypeError: list indices must be integers, not NoneType
@gxyd gxyd self-assigned this Jul 30, 2016
@jksuom jksuom closed this in 8a8cc97 Aug 22, 2016
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