Quantitative lower bounds for trace reconstruction

OpenAI

For every fixed deletion probability q∈(0,1), worst-case reconstruction of deterministic binary strings from independent deletion traces needs n^{Ω(log log n)} samples for any fixed positive success probability, even with unrestricted computation.

Sources for this record

What was already known

Earlier full-trace lower bounds were polynomial. A separate quasipolynomial-sample upper bound and a later uniform decoder concern the opposite direction.

AI involvement AI-led

OpenAI is credited as author and attributes its mathematical manuscripts to an internal model. No decisive human-origin repair of the lower-bound construction is disclosed.

OpenAI is credited as author and identifies the internal model as producer of these mathematical manuscripts and proof artifacts.

Importance Major

Rules out polynomial-sample worst-case reconstruction at every fixed deletion rate.

Limitations

The reported Lean scope covers the sample lower bound. The separate decoder has quasipolynomial samples and bit time for fixed known rational retention probability; its polynomial regime needs deletion probability at most n^(−ε).

Technical verification Formal (Lean 4)

The OpenAI Lean scope document maps the complete superpolynomial worst-case sample lower bound, including fixed q and arbitrary fixed positive success probability, to a TraceReconstruction comparator. This rating applies to the lower bound; no corresponding complete formal check of the October decoder is documented here.

Formal checking

Lean formalization linked by the TraceReconstruction comparator and family 122 scope document

Checker
OpenAI Lean 4 library and comparator
Scope
Superpolynomial sample lower bounds for worst-case binary trace reconstruction at fixed deletion probability, including the quantitative n^{c log(q^3 log n)} regime
Basis
Reported by the linked checker
Evidence source

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

Human understanding Few

The papers contain model-produced explanations, but no human explanation of the central multiscale lower-bound mechanism was located; Few is the evidence default.

Correction and publication history