OAI/NumberTheory/CubicMoment/Estimates/PrimeNormFibers.lean

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Norm fibers for a fixed number of primary prime factors

Equal norms give b * conjugate b = b₀ * conjugate b₀. Consequently every prime factor of b is one of the prime factors of b₀ or its conjugate. For products of k primary primes this bounds every norm fiber by (2 * k)^k, uniformly in all prime supports and the norm. No general divisor estimate is needed for the structured coefficients.

  1. lemma OAI.CubicFirstMoment.prime_tuple_norm_range_subset line 25

    Source documentation

    A prime in a tuple of the same norm must occur in the reference tuple or in its conjugate. Primary normalization turns association into equality.

    lemma prime_tuple_norm_range_subset (f g : ι → Eisenstein)
        (hf : ∀ i, primaryPrime (f i)) (hg : ∀ i, primaryPrime (g i))
        (hn : normNat (∏ i, g i) = normNat (∏ i, f i)) (i : ι) :
        g i ∈ Finset.univ.image f ∪ Finset.univ.image (fun j => conjugate (f j)) := by
    …

    Mentions: OAI.CubicFirstMoment.Eisenstein, OAI.CubicFirstMoment.primaryPrime, OAI.CubicFirstMoment.normNat, OAI.CubicFirstMoment.conjugate

  2. theorem OAI.CubicFirstMoment.primeProduct_norm_fiber_card line 48

    Source documentation

    The number of distinct products with a prescribed norm is bounded solely in terms of the number of prime factors, even with repetitions.

    theorem primeProduct_norm_fiber_card (S : ι → Finset Eisenstein)
        (hS : ∀ i, ∀ p ∈ S i, primaryPrime p) (n : ℕ) :
        ((orderedConvolutionSupport S).filter (fun b => normNat b = n)).card ≤
          (2 * Fintype.card ι) ^ (Fintype.card ι) := by
    …

    Mentions: OAI.CubicFirstMoment.Eisenstein, OAI.CubicFirstMoment.primaryPrime, OAI.CubicFirstMoment.orderedConvolutionSupport, OAI.CubicFirstMoment.normNat