OpenAI reports nontrivial Markov type forces superreflexivity

Every real Banach space with Markov type p>1 for some p is superreflexive; with the established converse, nontrivial Markov type characterizes superreflexivity.

Sources for this record

What was already known

Superreflexive spaces were known to have nontrivial Markov type, but Naor’s converse question remained open. Earlier metric characterizations used tree or diamond distortion rather than Markov type.

AI involvement AI-led

OpenAI credits itself as manuscript author and states that its internal frontier model produced the results in this release. Individual human input is not detailed enough to establish task-only autonomy.

OpenAI is named as author on the manuscript, and its release attributes the results to an internal frontier model. The individual human input is not detailed enough to establish autonomy.

Importance Major

Gives a Markov-chain metric characterization of superreflexivity.

Limitations

Markov type quantifies uniformly over finite stationary reversible chains and all positive times. The exponent and equivalent norm may depend on the space.

Technical verification Formal (Lean 4)

OpenAI reports a Lean proof matching the selected claim.

Formal checking

The pinned Lean note proves the equivalence between nontrivial Markov type, an equivalent uniformly convex norm and superreflexivity.

Checker
OpenAI-reported Lean 4 / Comparator
Scope
Every real Banach space with Markov type p>1 for some p is superreflexive; with the established converse, nontrivial Markov type characterizes superreflexivity.
Basis
Reported by the linked checker
Evidence source

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

Human understanding Few

Few is the default when evidence for a higher level is insufficient. No named person is documented as explaining the central argument for this assessed contribution.

Correction and publication history

2026-10-18 · publication

Primary manuscript, attribution, prior-work, and scoped checking review for non-notifying local inclusion.

Read this published revision