Decades-old problem in classical geometry solved Researchers at TUM refute Bonnet's rule of thumb. To do so, they construct two different donut-shaped surfaces with the same metric and mean curvature.

After many years of research, mathematicians found the first concrete example of a compact Bonnet pair. Two closed, donut-like surfaces share the same local #MeasurementData but do not determine a single global shape: go.tum.de/165037

#Geometry
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📷A.Eckert