Dimension formulas for level-one modular forms #
Mathlib (≥ v4.30.0) proves the level-one dimension formulas in
Mathlib.NumberTheory.ModularForms.LevelOne.DimensionFormula
(ModularForm.dimension_level_one, the rank lemmas for small weights, and
CuspForm.discriminantEquiv) and the identity Δ = (E₄³ - E₆²) / 1728 in
Mathlib.NumberTheory.ModularForms.LevelOne.GradedRing. Those results are stated for the
subgroup 𝒮ℒ; this file transports the ones the project uses to the Γ(1)-indexed
spaces used here (CongruenceSubgroup.Gamma_one_coe_eq_SL).
theorem
IsCuspForm_weight_lt_eq_zero
(k : ℤ)
(hk : k < 12)
(f : ModularForm (Subgroup.map (Matrix.SpecialLinearGroup.mapGL ℝ) (CongruenceSubgroup.Gamma 1)) k)
(hf : IsCuspForm (CongruenceSubgroup.Gamma 1) k f)
:
theorem
dim_gen_cong_levels
(k : ℤ)
(Γ : Subgroup (Matrix.SpecialLinearGroup (Fin 2) ℤ))
(hΓ : Γ.index ≠ 0)
: