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Formalized cmf LMFDB definitions - #81

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Formalized cmf LMFDB definitions#81
JaneShi99 wants to merge 8 commits into
CBirkbeck:mainfrom
JaneShi99:formalize/mf-defs

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IsGaloisConjugate, galoisOrbit, traceForm - though on LMFDB they're defined for only newforms, I kept the definition general for cusp forms.
Same with IsTwist, IsTwistRelated, dual/self-dual, self/inner twists, counts, CM/RM, twistMultiplicity.

I think everything else is faithful to the LMFDB side. The general rule is the following: if the construction makes sense to an arbitrary cusp form then we define it for a cusp form. If the definition genuinely depends on being a newform, we use IsNewform.

The Petersson product is now formalized as a genuine integral (mathlib's petersson integrand against its new invariant measure on ℍ, over a caller-supplied fundamental domain), while the definitions depending on it (newspace, eisensteinSubspace, IsNewform) take an abstract pairing B as input, so they can later be specialized to the concrete Petersson product without restating them.

(This is outside of my knowledge) but Claude gave me one caveat: the IsFundamentalDomain hypothesis is unsatisfiable for any group containing −I (e.g. SL(2,ℤ), Γ₀(N)) since −I acts trivially on ℍ — fixing this needs a PSL(2,ℤ)-style reformulation, and making the product non-junk still awaits three mathlib gaps: 𝒟 as a measure-theoretic fundamental domain, finiteness of its volume, and a finite-index coset-transfer lemma.

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