Exponential semidefinite complexity for perfect matching
Status OpenLLM status Open unverified
Top Open Problems unknownunknown Not reported cataloguedOpenOpenStatement
Definitions and mathematical statement
Statement recorded in the supplied source.
For every fixed shift $\rho \in (0,1)$, do the matrices indexed by odd vertex sets U and perfect matchings M, with entry $|M\cap \delta (U)|-1+\rho $, where $\delta (U)$ is the set of edges crossing U, of complete graphs on even n vertices require real positive-semidefinite factorization rank at least $2^{cn}$, for one $c>0$ independent of $\rho $ and all sufficiently large n depending on $\rho $? This also asks for the resulting exponential exact semidefinite-lift lower bound.Short English statement
For every fixed shift $\rho \in (0,1)$, do the matrices indexed by odd vertex sets U and perfect matchings M, with entry $|M\cap \delta (U)|-1+\rho $, where $\delta (U)$ is the set of edges crossing U, of complete graphs on even n vertices require real positive-semidefinite factorization rank at least $2^{cn}$, for one $c>0$ independent of $\rho $ and all sufficiently large n depending on $\rho $? This also asks for the resulting exponential exact semidefinite-lift lower bound.Sources
- S1 Original question source or mathematical context. https://arxiv.org/pdf/1704.01929.
- S2 OpenAI, manuscript citation page. Source of the formulation motivating this local problem. https://github.com/openai/math/blob/adc7f1241b42e322a6451854ab7e4b4c146bf78a/preprints/Exponential-PSD-rank-of-positively-shifted-matching-matrices-October-5-2026/README.md.
Statement licence: CC-BY-4.0 · Source file
Contributions 1
OpenAI claim summary for CS-139
The result supplies the conclusion in this problem with its displayed hypotheses and quantifiers. The broader statements and applications in the manuscript are kept separate from the particular question above. The supporting result is manuscript 1 (family 126; 2026-10-05).
Exponential semidefinite complexity for perfect matching
OpenAI's claim
OpenAI presents the following claims relevant to this question, with manuscript numbers following paper order in Sources. In manuscript 1 (family 126; 2026-10-05), the asserted result is that each fixed positive shift below one in the matching slack matrix has exponential real PSD rank, implying exponential size for exact semidefinite lifts of the matching polytope.Mathematical statement of the claimed result
Manuscript 1.
For even $n\ge4$, index rows by odd subsets $U\subseteq[n]$ and columns by perfect matchings $M$ of $K_n$, and define \[ A_n(\rho)_{U,M}=|M\cap\delta(U)|-1+\rho. \] Real PSD rank is the smallest $r$ permitting exact factorizations $A_{U,M}=\operatorname{tr}(F_UG_M)$ with real symmetric positive semidefinite $r\times r$ matrices. The asserted bound is \[ \exists c>0\ \forall\rho\in(0,1)\ \exists n_0(\rho)\ \forall\text{ even }n\ge n_0(\rho):\quad \operatorname{rank}_{\rm psd}A_n(\rho)\ge2^{cn}. \] The exponential constant is uniform in $\rho$, but the threshold may depend on it. No symmetry or precision restrictions are imposed on the factors.Outline of the argument
For manuscript 1 (family 126; 2026-10-05), coordinatewise product averages are expressed as sums of matrix squares. Orthogonal frequency splitting bounds a Gram potential through the averaging process; matching smoothing and an expanding parity system force a rank large enough to support the remaining Fourier mass.Formal verification
For manuscript 1 (family 126; 2026-10-05), the documented Lean scope is superpolynomial PSD rank for the selected matching slack matrix and superpolynomial size of exact lifts; the claimed exponential bound for every fixed positive shift is outside the selected statement.This coverage does not establish a formal proof of the complete problem as stated here.
The linked family Comparator checks are MatchingAffineLift.lean, MatchingPSD.lean.
Their named declarations include OAI.PerfectMatchingPSD.affine_lift_lower_bound, OAI.PerfectMatchingPSD.main.
This site has not executed the Lean code. Described statement coverage is not an independent proof check.
Status caveat
The manuscripts were produced by an internal OpenAI model. OpenAI cautions that results without formalization can contain mistakes. This site has not independently checked the proofs; the label records the scope of OpenAI's claim.Sources
- OpenAI, Exponential PSD rank of positively shifted matching matrices, 2026-10-05; citation key
OAI:Exponential-PSD-rank-of-positively-shifted-matching-matrices-October-5-2026. PDF (GitHub); PDF (direct); Manuscript page and citation; Latest version; Statement source: thm:main. - Family 126: Lean scope.
- Comparator MatchingAffineLift.json.
- Comparator MatchingAffineLift.lean.
- Comparator MatchingPSD.json.
- Comparator MatchingPSD.lean.
- OpenAI catalogue entry.