Mario Ullrich

activity

20242026

most citedApproximation of Functions: Optimal Sampling and Complexity

2 citations · 2 across the 2 of their papers we have counts for

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4 papers · 1 filter

math.FA2026

On bounds between all s-numbers and widths of convex sets

Mario Ullrich

We prove $a_{n} (S) \leq e (n + 1) s_{n} (S)$ for every s-number sequence $(s_{n})$ , every bounded linear operator $S$ between normed spaces, and every $n \in N_{0}$ , where $a_{n}$ ar…

math.FA2025

Sampling and entropy numbers in the uniform norm

Mario Ullrich

We prove a sharp bound between sampling numbers and entropy numbers in the uniform norm for bounded convex sets of bounded functions.

math.FA2025

Sampling projections in the uniform norm

David Krieg, Kateryna Pozharska, Mario Ullrich +1

We show that there are sampling projections on arbitrary $n$ -dimensional subspaces of $B (D)$ with at most $2 n$ samples and norm of order $n$ , where $B (D)$ is the space of co…

math.FA2024

Inequalities between s-numbers

Mario Ullrich

Singular numbers of operators between Hilbert spaces were generalized to Banach spaces by s-numbers (in the sense of Pietsch). This allows for different choices, including approxim…