#10453: Problem with old submodule
-----------------------------+----------------------------------------------
Reporter: davidloeffler | Owner: craigcitro
Type: defect | Status: new
Priority: major | Milestone: sage-4.6.2
Component: modular forms | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
-----------------------------+----------------------------------------------
Description changed by davidloeffler:
Old description:
> If you ask for the old submodule of a Gamma1 modular forms space, and
> that old subspace is actually zero, then Sage crashes:
>
> {{{
> sage: CuspForms(Gamma1(11), 2).old_submodule()
> ERROR: An unexpected error occurred while tokenizing input
> The following traceback may be corrupted or invalid
> The error message is: ('EOF in multi-line statement', (28, 0))
>
> ---------------------------------------------------------------------------
> ValueError Traceback (most recent call
> last)
>
> /home/masiao/<ipython console> in <module>()
>
> /usr/local/sage/sage-4.6/local/lib/python2.6/site-
> packages/sage/modular/hecke/submodule.pyc in old_submodule(self, p)
> 850 pass
> 851
> --> 852 S = self.ambient_hecke_module().old_submodule(p)
> 853 os = S.intersection(self)
> 854 if os.rank() == self.rank():
>
> /usr/local/sage/sage-4.6/local/lib/python2.6/site-
> packages/sage/modular/hecke/ambient_module.pyc in old_submodule(self, p)
> 857 #end if
> 858 #end for
> --> 859 os = self.submodule(d.image(), check=False)
> 860 self.__is_old[p] = (os == self)
> 861
>
> /usr/local/sage/sage-4.6/local/lib/python2.6/site-
> packages/sage/modular/hecke/ambient_module.pyc in submodule(self, M,
> Mdual, check)
> 887 if M == self.free_module():
> 888 return self
> --> 889 return self._submodule_class()(self, M, Mdual,
> check=check)
> 890
> 891 def _submodule_class(self):
>
> /usr/local/sage/sage-4.6/local/lib/python2.6/site-
> packages/sage/modular/modform/submodule.pyc in __init__(self,
> ambient_module, submodule, dual, check)
> 46 """
> 47 A = ambient_module
> ---> 48
> sage.modular.hecke.submodule.HeckeSubmodule.__init__(self, A, submodule,
> check=check)
> 49 space.ModularFormsSpace.__init__(self, A.group(),
> A.weight(),
> 50 A.character(),
> A.base_ring())
>
> /usr/local/sage/sage-4.6/local/lib/python2.6/site-
> packages/sage/modular/hecke/submodule.pyc in __init__(self, ambient,
> submodule, dual_free_module, check)
> 85 raise TypeError, "submodule must be a free module"
> 86 if not submodule.is_submodule(ambient.free_module()):
> ---> 87 raise ValueError, "submodule must be a submodule of
> the ambient free module"
> 88
> 89 if check:
>
> ValueError: submodule must be a submodule of the ambient free module
> }}}
New description:
Weird things happen if you try to compute the old submodule of a Gamma1
modular forms space. E.g.
{{{
sage: CuspForms(Gamma1(11), 2).old_submodule() # crashes
}}}
This turns out to be because:
{{{
sage: ModularForms(Gamma1(11),
2).hecke_module_of_level(1).hecke_module_of_level(11)
Modular Forms space of dimension 2 for Congruence Subgroup Gamma0(11) of
weight 2 over Rational Field
}}}
so the degeneracy level-raising map is getting computed for the wrong
space!
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10453#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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