Non-freezing of the proximity digraph and non-pseudostable convergence in heterogeneous Hegselmann--Krause models: Counterexamples to conjectures and results of Mirtabatabaei and Bullo

Peter Hegarty, Damiano Ognissanti, Edvin Wedin

Hegarty, Ognissanti and Wedin give convergent heterogeneous Hegselmann–Krause trajectories in the synchronized bounded-confidence and bounded-influence models whose proximity digraphs never stabilize, plus constant-digraph trajectories that fail eventual pseudostability. These counterexamples refute Mirtabatabaei and Bullo Conjectures 2.2 and 2.3 and Theorem 6.4(iv).

Sources for this record

What was already known

Mirtabatabaei and Bullo proposed graph stabilization and eventual pseudostability in these models. Their main conjecture that every trajectory converges remains open.

AI involvement AI-led

The three authors credit Claude Opus 5.5 with finding the examples after their prompts. They wrote the explanations and checked every example by hand; JD Jones directed the later Lean formalization.

The authors explicitly credit Claude Opus 5.5 with finding the retained counterexamples after their prompts.

Importance Notable

The examples overturn two conjectures and one theorem about heterogeneous opinion dynamics.

Limitations

The later Lean work also contains smaller examples and extensions, which are separate from these four paper examples.

Technical verification Formal (Lean 4.35.0-rc2/Mathlib + human)

The paper authors report checking all four examples by hand, and the cited Lean development reports complete proofs of their closed forms, neighborhood tables and refutations. These are two documented checks of the same paper examples; the later repository’s extra systems are outside this assessment.

Formal checking

Hand verification of the examples and written proofs

Checker
Hegarty, Ognissanti and Wedin
Scope
The explicit SBC and SBI counterexample trajectories in §§2–5
Basis
Reported by the linked checker
Evidence source

Formal checking

Lean proof build and axiom audit

Checker
Lean 4 kernel in JD Jones’s reported build
Scope
Closed forms, neighborhoods, convergence and refutations for the four paper systems
Basis
Reported by the linked checker
Evidence source

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

Human understanding Full

The human authors explain the explicit trajectories, alternating modes, and why these defeat the earlier claims. Their prose and hand check cover the central mechanism of the assessed examples.

Correction and publication history

2026-10-18 · publication

The examples overturn two conjectures and one theorem about heterogeneous opinion dynamics.

Read this published revision