English
There exists a variable change C such that C • W is minimal over R.
Русский
Существует переменная смены C такая, что C • W минимальна по отношению к R.
LaTeX
$$$\\exists C : VariableChange K,\\; \\text{IsMinimal } R (C \\cdot W)$$$
Lean4
theorem exists_isMinimal (W : WeierstrassCurve K) : ∃ C : VariableChange K, IsMinimal R (C • W) :=
by
obtain ⟨C, hC⟩ :=
exists_maximalFor_of_wellFoundedGT (fun (C : VariableChange K) ↦ IsIntegral R (C • W))
(fun (C : VariableChange K) ↦ valuation_Δ_aux R (C • W)) (exists_isIntegral R W)
refine ⟨C, ⟨⟨by simp only [one_smul, hC.1], ?_⟩⟩⟩
intro j hj; rw [← smul_assoc] at hj
let h := hC.2 hj
simp_all only [one_smul]
rw [← smul_assoc]
exact h