A Kernel-Certified Verification of the Erdős-Mollin-Walsh Conjecture below $10^{14}$
Ibrahim Mian, Shayaan Siddique
math.GM
Jul 29, 2026 · v1
cs.LO
TL;DR
Proves in Lean 4 with Mathlib, via kernel-checked decide certificates, that no three consecutive powerful numbers exist below 10^12 and 10^14.
Abstract
Erdős problem 364 asks whether three consecutive powerful numbers exist, where $n$ is powerful if $p \mid n$ implies $p^2 \mid n$. Erdős (1976) and, independently, Mollin and Walsh (1986) conjectured that none do; the $abc$ conjecture implies at most finitely many. The conjecture remains open. We present the first verification of the conjecture at any finite bound that is checked end to end by a proof kernel: machine-checked theorems in Lean 4 establishing that no triple of consecutive powerful numbers exists below $10^{12}$ and below $10^{14}$, with the axiom footprint of both theorems being exactly {propext, Classical.choice, Quot.sound} – no sorry, no native_decide, no trusted external computation. The statements are phrased in the byte-identical vocabulary of the google-deepmind/formal-conjectures formalization of the problem, and we prove abstractly that the open conjecture implies each bounded form, pinning the statement correspondence. The proof reduces the search to odd numbers via a mod-4 argument, represents every odd powerful number as $a^2 b^3$ with $a, b$ odd and $b$ squarefree, enumerates all odd powerful numbers by a fueled, kernel-reducible generator whose completeness is proved once and instantiated across 3,524 per-interval Boolean certificates, and eliminates the seven surviving distance-2 pairs (the members of OEIS A076445 below $10^{14}$) by explicit non-powerfulness witnesses. Every certificate's expected values are computed independently by a Python engine, so each kernel-checked equality doubles as a cross-implementation agreement. Total certified kernel time is roughly 46 CPU-hours. Larger uncertified computations exist (exhaustive to $10^{22}$; conditionally to about $7.38 \times 10^{28}$); our contribution is not a computational record but the elimination of trusted enumeration code from the evidence chain.
Problem
Erdős problem 364 conjectures that no three consecutive powerful numbers exist. Existing computational evidence, exhaustive to 10^22, relies on trusted, uncertified enumeration code.
Approach
The search is reduced to odd powerful pairs at distance 2 by a mod-4 argument. Odd powerful numbers are represented as a^2 b^3 with b squarefree and enumerated by a fueled, kernel-reducible generator whose completeness is proved once. That generator is used in 3,524 per-interval Boolean certificates checked by decide, without native_decide. The seven surviving pairs are eliminated with explicit non-powerfulness witnesses, and statements reuse the byte-identical Powerful definition from google-deepmind/formal-conjectures.
Results
Lean theorems establish that no powerful triple exists below 10^12 and below 10^14, with axiom footprint exactly {propext, Classical.choice, Quot.sound}. Total certified kernel time is about 46 CPU-hours, and Python-computed expected values provide cross-implementation agreement.
| X=10^12 | X=10^14 |
|---|
| chunk certificates | 320 | 3,204 |
| kernel time | 57,652 s (~16 CPU-h) | 107,603 s (~30 CPU-h) |
| max single chunk | ~305 s | 61 s |
| pairs found | 5 | 7 |
Certified computation cost per bound