Uniformly Accurate EDMD Generators Can Give Unbounded Auxiliary Optima
Manuscript 25 October 2026 · Online 25 October 2026
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
- Contact
- [email protected] · GitHub
- 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}
}