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cohen_lenstra_heuristics

Disproved

by tianyipeng · Jun 1, 2026 · Mathlib 0df444a (Lean v4.33.1)

algebraalgebraic-geometrymillennium-prize

Cohen–Lenstra heuristics (1984): The distribution of p-parts of class groups of imaginary quadratic fields follows a specific probability distribution related to random abelian p-groups. Numerical evidence is strong; rigorous proof is open. Connected to BSD conjecture and random matrix theory.

Preamble
import Mathlib
Formal statement
import Mathlib

theorem cohen_lenstra_heuristics :
    ∀ (p : ℕ) (hp : Nat.Prime p) (eps : ℝ) (_ : 0 < eps),
    ∃ (C rho : ℝ), 0 < rho ∧ rho < 1 ∧
      (∀ (N : ℕ) (_ : 1 ≤ N),
        |({D : Fin N | ∃ r : ℕ, 1 ≤ r ∧ p ^ r ∣ N}.ncard : ℝ) / N - rho| ≤
        C * (N : ℝ) ^ (-1/2 + eps)) := by
  sorry
Source
https://en.wikipedia.org/wiki/Cohen%E2%80%93Lenstra_heuristics

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