Strong Ulam Stability Characterizes Amenability

OpenAI

For every countable discrete group, the manuscript claims amenability is equivalent to strong Ulam stability: sufficiently accurate unitary almost representations on any complex Hilbert space are uniformly close in operator norm to genuine representations on the same space. It gives a fixed-distance obstruction for nonamenable groups.

Sources for this record

What was already known

Kazhdan proved the amenable direction. Burger, Ozawa and Thom asked about the converse and established it for groups containing nonabelian free subgroups; other partial classes were known.

AI involvement AI-led

OpenAI credits an internal model with the manuscript. The amenable direction and earlier nonamenable-group cases are human results.

OpenAI authorship and release provenance attribute the mathematical manuscript to internal-model work, without evidence of autonomous session conditions.

Importance Notable

The converse answers the question for all countable discrete groups.

Limitations

No completed check of the strong Ulam proof is documented. Finite-dimensional stability is a different property, and the companion Dixmier formalization does not verify this theorem.

Technical verification Reported

No completed human or machine check of the strong Ulam theorem is documented. The Lean scope for the companion Dixmier result cannot be transferred to it. Reported is the evidence default.

Human understanding Few

No named human explanation of the new flag, circuit and quadratic-form obstruction is documented. Few is the evidence default.

Correction and publication history