Aperiodic maximisers of Lyapunov dimension: A counterexample to the unrestricted form of Eden's conjecture

Matthew Colbrook

For each c>4, Colbrook’s polynomial ODE on ℝ⁵ has uniformly negative divergence and a compact global attractor. Its finite-time local Lyapunov and asymptotic Kaplan–Yorke dimension maxima are 4+4/c on an irrational-flow invariant two-torus, while equilibrium and periodic-point maxima are 3.

Sources for this record

What was already known

Unrestricted Eden predicted that a dimension maximum on such an attractor occurs at an equilibrium or periodic orbit.

AI involvement AI-centered

Colbrook reports that Codex found the counterexample after an earlier attempted proof. He checked the argument and formulation; ChatGPT 6 assisted later Lean verification.

Codex supplied the counterexample in a human-led project, establishing a central model construction; proof and formalization had human oversight.

Importance Notable

Refutes the unrestricted conjecture with an explicit dynamical system.

Limitations

The construction does not address stronger transitivity or typical-attractor variants. The formal theorem covers the stated ODE and dimension comparison, while the historical interpretation of Eden’s conjecture is external to Lean.

Technical verification Formal (Lean 4.33.1 with Mathlib and Lean Comparator + human)

The author reports checking the argument and the formalization documents a complete kernel-checked theorem tied to the paper. These are source-reported, not locally reproduced.

Independent checking

complete Lean proof, statement comparison and axiom audit

Checker
Lean kernel via Colbrook formalization
Scope
paper Theorem 1.1 and Palomar main theorem, including ODE/flow and dimension maxima
Basis
Reported by the linked checker

author’s explicit proof/formulation check and adoption

Checker
Matthew J. Colbrook
Scope
original counterexample proof and problem formulation
Basis
Reported by the linked checker
Evidence source

Human understanding Full

Colbrook’s paper and reading guide explain the radial dynamics, aperiodic maximizing torus and dimension comparison.

Correction and publication history