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math.AP2015
Some nodal properties of the quantum harmonic oscillator and other Schr{ö}dinger operators in
Pierre Bérard, Bernard Helffer
For the spherical Laplacian on the sphere and for the Dirichlet Laplacian in the square}, Antonie Stern claimed in her PhD thesis (1924) the existence of an infinite sequence of ei…
math.AP2015★ 26 cited
Courant-sharp eigenvalues for the equilateral torus, and for the equilateral triangle
Pierre Bérard, Bernard Helffer
We address the question of determining the eigenvalues (listed in nondecreasing order, with multiplicities) for which Courant's nodal domain theorem is sharp i.e., for which…