AlexKontorovich/PrimeNumberTheoremAnd
Source indexedtheorem · leanprover/lean4:v4.32.0
Lcm.Criterion.not_highlyAbundant_2
PrimeNumberTheoremAnd.IEANTN.Lcm · PrimeNumberTheoremAnd/IEANTN/Lcm.lean:730 to 771
Source documentation
Combining Lemma \ref{lem:criterion-sufficient} with Lemma \ref{lem:sigmaLn}, we see that it suffices to bound (\sigma(M)/M) from below in terms of (\sigma(L')/L'):
Exact Lean statement
@[blueprint
"lem:criterion-reduced"
(title := "Reduction to a lower bound for \\(\\sigma(M)/M\\)")
(statement := /--
If
\begin{equation}\label{eq:sigmaM-lower}
\frac{\sigma(M)}{M}
\;\ge\;
\frac{\sigma(L')}{L'}
\Biggl( \prod_{i=1}^3 \Bigl(1+\frac{1}{p_i(p_i+1)}\Bigr) \Biggr)
\Bigl(1 + \frac{3}{8n}\Bigr),
\end{equation}
then $L_n$ is not highly abundant.
-/)
(proof := /--
Insert \eqref{eq:sigmaM-lower} and \eqref{eq:sigmaLn} into the desired inequality and compare
with the assumed bound \eqref{eq:main-ineq}; this is a straightforward rearrangement.
-/)
(proofUses := ["lem:sigmaLn", "lem:criterion-sufficient"])
(latexEnv := "lemma")]
theorem Criterion.not_highlyAbundant_2 (c : Criterion)
(h : σnorm c.M ≥ σnorm c.L' * (∏ i, (1 + 1 / (c.p i * (c.p i + 1 : ℝ)))) *
(1 + (3 : ℝ) / (8 * c.n))) : ¬HighlyAbundant (L c.n)Complete declaration
Lean source
Full Lean sourceLean 4
@[blueprint "lem:criterion-reduced" (title := "Reduction to a lower bound for \\(\\sigma(M)/M\\)") (statement := /-- If \begin{equation}\label{eq:sigmaM-lower} \frac{\sigma(M)}{M} \;\ge\; \frac{\sigma(L')}{L'} \Biggl( \prod_{i=1}^3 \Bigl(1+\frac{1}{p_i(p_i+1)}\Bigr) \Biggr) \Bigl(1 + \frac{3}{8n}\Bigr), \end{equation} then $L_n$ is not highly abundant. -/) (proof := /-- Insert \eqref{eq:sigmaM-lower} and \eqref{eq:sigmaLn} into the desired inequality and compare with the assumed bound \eqref{eq:main-ineq}; this is a straightforward rearrangement. -/) (proofUses := ["lem:sigmaLn", "lem:criterion-sufficient"]) (latexEnv := "lemma")]theorem Criterion.not_highlyAbundant_2 (c : Criterion) (h : σnorm c.M ≥ σnorm c.L' * (∏ i, (1 + 1 / (c.p i * (c.p i + 1 : ℝ)))) * (1 + (3 : ℝ) / (8 * c.n))) : ¬HighlyAbundant (L c.n) := by refine c.not_highlyAbundant_1 ?_ have hL'_pos : 0 < σnorm c.L' := by rw [σnorm]; exact div_pos (cast_pos.mpr <| by rw [σ, sigma_pos_iff]; exact c.L'_pos) (cast_pos.mpr c.L'_pos) have hR_pos : (0 : ℝ) < 1 - 4 * (∏ i, c.p i) / (∏ i, c.q i) := by rw [sub_pos, div_lt_one (cast_pos.mpr <| prod_pos fun i _ ↦ (c.hq i).pos)] exact_mod_cast c.prod_p_le_prod_q have hcrit : (∏ i, (1 + (1 : ℝ) / c.q i)) ≤ (∏ i, (1 + 1 / (c.p i * (c.p i + 1 : ℝ)))) * (1 + 3 / (8 * c.n)) * (1 - (4 : ℝ) * (∏ i, c.p i) / (∏ i, c.q i)) := by convert c.h_crit using 3; simp only [prod_natCast] rw [c.σnorm_ln_eq] calc σnorm c.L' * ∏ i, (1 + (1 : ℝ) / c.q i) ≤ σnorm c.L' * ((∏ i, (1 + 1 / (c.p i * (c.p i + 1 : ℝ)))) * (1 + 3 / (8 * c.n)) * (1 - (4 : ℝ) * (∏ i, c.p i) / (∏ i, c.q i))) := mul_le_mul_of_nonneg_left hcrit hL'_pos.le _ = σnorm c.L' * (∏ i, (1 + 1 / (c.p i * (c.p i + 1 : ℝ)))) * (1 + 3 / (8 * c.n)) * (1 - (4 : ℝ) * (∏ i, c.p i) / (∏ i, c.q i)) := by ring _ ≤ σnorm c.M * (1 - (4 : ℝ) * (∏ i, c.p i) / (∏ i, c.q i)) := mul_le_mul_of_nonneg_right h hR_pos.le