Kourovka Problem 3.46: Exactly two maximal locally soluble normal subgroups

A group with exactly two maximal locally soluble normal subgroups, resolving Kourovka Problem 3.46.

Sources for this record

What was already known

Earlier examples had infinitely many such maximal subgroups; the Notebook asked whether a finite number greater than one is possible.

AI involvement AI-autonomous

Van Doorn, Judin, Monticone and Morrison report that Aristotle developed the proof strategy and Lean proof without human guidance on mathematical steps. The authors chose problems, supplied infrastructure, refined the formal code, translated the proofs into prose and arranged external review.

The authors say Aristotle developed the new mathematical argument and formal proof strategy without human guidance on the mathematical steps. Humans selected the task, supplied infrastructure, refined the code and wrote the prose account.

Importance Notable

A new construction answers a group theory question posed in the 1969 Notebook.

Limitations

The construction concerns locally soluble normal subgroups in an infinite group; it does not classify all possible finite counts.

Technical verification Formal (Lean 4)

The companion metadata names declaration kourovka_3_46 and reports a complete Lean proof with zero sorry. This is a source-reported machine check of the scoped theorem; the assessment did not compile the project.

Formal checking

The authors report a Lean 4 proof with zero sorry for declaration kourovka_3_46.

Checker
Lean 4
Scope
A group with exactly two maximal locally soluble normal subgroups, resolving Kourovka Problem 3.46.
Basis
Reported by the linked checker
Evidence source

Checking a formal statement does not establish that it matches the original problem.

Human understanding Full

Van Doorn, Judin, Monticone and Morrison translated the formal solution, refined the explanation and present the construction or proof in mathematical prose. This documents human explanation of the central argument.

Correction and publication history

2026-10-18 · publication

Primary-source review of the scoped Kourovka result, AI contribution, Lean checking, human prose proof and prior baseline. Historical, non-notifying addition.

Read this published revision