The Brandt module associated to the supersingular module M.
Proof: BoolElt Default: true
The space of modular symbols corresponding to the supersingular module M.
Proof: BoolElt Default: true
The +1 or -1 quotient of the space of modular symbols
corresponding to the supersingular module M.
The Z-module V underlying the supersingular module M along with an invertible map
V -> M.
We compute the Brandt module and modular symbols spaces associated
to the supersingular module for p=3, N=11, and verify that
T
2 has the same characteristic polynomial on each.
> M := SupersingularModule(3,11);
> B := BrandtModule(M); B;
Brandt module of level (3,11), dimension 2, and degree 2 over
Integer Ring
> MS := ModularSymbols(M); MS;
Modular symbols space for Gamma_0(33) of weight 2 and dimension 4
over Rational Field
> Factorization(CharacteristicPolynomial(HeckeOperator(B, 2)));
[
<$.1 - 3, 1>,
<$.1 - 1, 1>
]
> Factorization(CharacteristicPolynomial(HeckeOperator(MS, 2)));
[
<$.1 - 3, 2>,
<$.1 - 1, 2>
]
There is an associated Brandt module even if the underlying computations
on M are done using the Mestre-Oesterle graph method.
> M := SupersingularModule(11);
> UsesMestre(M);
true
> B := BrandtModule(M); B; // takes a while
Brandt module of level (11,1), dimension 2, and degree 2 over
Integer Ring
V2.28, 13 July 2023