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Transport and Interface: an Uncertainty Principle for the Wasserstein distance

2019/05/17 by Sagiv, Amir, Steinerberger, Stefan
#Classical Analysis and ODEs (math.CA) #FOS: Mathematics #Metric Geometry (math.MG)

paper · doi:10.48550/arxiv.1905.07450

Abstract

Let f: [0,1]d → ℝ be a continuous function with zero mean and interpret f+ = max(f, 0) and f- = -min(f, 0) as the densities of two measures. We prove that if the cost of transport from f+ to f- is small (in terms of the Wasserstein distance W1), then the nodal set \x ∈ (0,1)d: f(x) = 0 \ has to be large (`if it is always easy to buy milk, there must be many supermarkets'). More precisely, we show that W1(f+, f-) ⋅ Hd-1\x ∈ (0,1)d: f(x) = 0 \ \gtrsimd ( \frac‖f‖L1‖f‖L )4 - \frac1d ‖f‖L1 . We apply this ``uncertainty principle" to the metric Sturm-Liouville theory in higher dimensions to show that a linear combination of eigenfunctions of an elliptic operator cannot have an arbitrarily small zero set.

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