4 papers
Ricci curvature for fluid models on the torus via Zeitlin's quantization
Sadashige Ishida, Alex Suri
Ricci curvature measures the average stability of geodesics under transverse perturbations, but how it should be defined in infinite dimensions is often unclear. This paper propose…
L'Hopital rules for complex-valued functions in higher dimensions
Albert Chern, Sadashige Ishida
In calculus, l'Hopital's rule provides a simple way to evaluate the limits of quotient functions when both the numerator and denominator vanish. But what happens when we move beyon…
Implicit representations of codimension-2 submanifolds and their prequantum structure
Albert Chern, Sadashige Ishida
This paper explores the geometry of the space of codimension-2 submanifolds. We implicitly represent these submanifolds by a class of complex-valued functions. We show that the spa…
Symplectic structures on the space of space curves
Martin Bauer, Sadashige Ishida, Peter W. Michor
We present symplectic structures on the shape space of unparameterized space curves that generalize the classical Marsden-Weinstein structure. Our method integrates the Liouville 1…