Commit 2026-09-22 10:29 edcc2ee7

feat(NumberTheory/ModularForms): restrict a mod form to a subgroup (#43756) For 𝒢 ≤ ℋ subgroups of GL(2, ℝ), define the natural map from modular forms of level ℋ to modular forms of level 𝒢 (the identity on underlying functions). Also refactor some related existing code (translation and norm/trace maps) to gather it together in one file.