Browsing 2020 by Author "Bruschi, David Edward"
Now showing items 1-2 of 2
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From Betti numbers to ℓ²-Betti numbers
[SNAP-2020-001-EN] Kammeyer, Holger; Sauer, Roman (Mathematisches Forschungsinstitut Oberwolfach, 2020-04-15)We provide a leisurely introduction to ℓ²-Betti numbers, which are topological invariants, by relating them to their much older cousins, Betti numbers. In the end we present an open research problem about ℓ²-Betti numbers. -
Rotating needles, vibrating strings, and Fourier summation
[SNAP-2020-006-EN] Zahl, Joshua (Mathematisches Forschungsinstitut Oberwolfach, 2020-09-21)We give a brief survey of the connection between seemingly unrelated problems such as sets in the plane containing lines pointing in many directions, vibrating strings and drum heads, and a classical problem from Fourier analysis.