OWR-14298803-004 · Complete scoped counterexample

Uniformly Accurate EDMD Generators Can Give Unbounded Auxiliary Optima

Manuscript 25 October 2026 · Online 25 October 2026

math.DSmath.OCmath.NAUnrefereed preprint

Abstract

We construct noiseless data for which extended dynamic mode decomposition (EDMD) converges uniformly to the true generator on a fixed polynomial auxiliary space, while the associated unregularized auxiliary optimum is minus infinity instead of 1. For dx/dt = -x^5 on [-1,1], we use quadratic auxiliaries and a degree-six dictionary. The regression has full column rank. The theorem holds for every N >= 9 Chebyshev-node design and, almost surely, for all sufficiently large iid datasets from the full-support arcsine measure. A uniform negative-derivative certificate holds for every 0 < tau <= 2^(-26), while the operator error is bounded by 156 tau in the stated coefficient norm. Adding the valid constraint U >= 0 makes the approximate value finite but still incorrect. The qualitative strict-feasibility obstruction is known from Bramburger and Fantuzzi; this note gives an actual exact-flow realization and elementary regularization bounds. It does not close the general optimal-value error-estimation problem or contradict prior convergence theorems. This is an unrefereed, AI-assisted preprint without an absolute priority claim.

Record

Affiliation
Mercury Software GmbH
Result
Complete scoped counterexample
Categories
math.DS · math.OC · math.NA
Manuscript
25 October 2026
Online release
25 October 2026
Version
1.0
License
Creative Commons Attribution 4.0 International

Files and verification

The PDF is the canonical reading copy. The source archive contains the LaTeX manuscript, bibliography, reproducibility material, and audit documents without build artefacts.

Citation

Alper Ferudun, “Uniformly Accurate EDMD Generators Can Give Unbounded Auxiliary Optima,” EulerSolve Research Papers, OWR-14298803-004, 2026. https://doi.org/10.5281/zenodo.23627738.

BibTeX
@misc{ferudun2026edmdinstability,
  author = {Ferudun, Alper},
  title = {Uniformly Accurate EDMD Generators Can Give Unbounded Auxiliary Optima},
  year = {2026},
  howpublished = {EulerSolve Research Papers},
  url = {https://eulersolve.org/papers/owr-14298803-004/},
  doi = {10.5281/zenodo.23627738},
  note = {OWR-14298803-004; unrefereed preprint}
}

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