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Extension of the Alberti–Marchese structure theorem beyond finite-dimensional Euclidean spaces

Ascertain whether the Alberti–Marchese structure theorem (Theorem 1.1 in Alberti–Marchese), which represents a classical k-dimensional flat chain in ℝ^n as the restriction of a boundaryless normal k-current with controlled mass, extends to ambient spaces beyond finite-dimensional Euclidean space (for example, to Banach spaces) in dimensions k ≥ 2.

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Background

The proof strategy for representing currents as restrictions of boundaryless normal currents relies on a strict polyhedral approximation theorem. This paper establishes such an approximation for k=1 in spaces with a conical geodesic bicombing, enabling a Banach-space extension in dimension 1.

For k≥2, the strict polyhedral approximation fails in infinite-dimensional Hilbert spaces, and thus current techniques do not directly yield an extension of the Alberti–Marchese theorem beyond finite-dimensional Euclidean settings. Whether an analogue holds more generally remains unresolved.

References

For $k\geq 2$, the above strict approximation result fails in every infinite-dimensional Hilbert space and, therefore, it is currently unclear if Theorem 1.1 can be extended beyond finite dimensional Euclidean space.

Structure of Metric $1$-currents: approximation by normal currents and representation results (2508.08017 - Bate et al., 11 Aug 2025) in Introduction, Subsection 'Main ideas on the proof of the representation theorem', Step 1