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Stability of magnitude for finite subsets of Euclidean and taxicab spaces

Prove that for U = (ℝ^n, ℓ^p) with 1 ≤ p ≤ 2, the magnitude mapping X ↦ |X| is continuous with respect to the Hausdorff topology on the set of finite subsets of U, thereby establishing stability of magnitude for finite subsets of Euclidean (ℓ^2) and taxicab (ℓ^1) spaces.

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Background

The conjecture isolates a practically important setting: finite subsets in ℝn with ℓp metrics (p ∈ [1,2]), which are positive definite and central to applications in data analysis and machine learning. A proof would furnish a robust stability theorem compatible with standard embedding contexts.

This conjecture is motivated by both the failure of generic continuity in Formulation A and the partial success along lines in Formulation B, suggesting that continuity may hold in widely used ambient spaces despite pathological behavior in general Gromov–Hausdorff space.

References

We therefore close this introduction by stating a conjecture. If U = (\mathbb{R}n, \ellp) where 1 \leq p \leq 2, then the function X \mapsto |X| is continuous with respect to the Hausdorff topology on the set of finite subsets of U. In particular, magnitude is stable for finite subsets of Euclidean or taxicab space.

Is magnitude 'generically continuous' for finite metric spaces? (2501.08745 - Katsumasa et al., 15 Jan 2025) in Introduction, end (Conjecture 1.3)