Eg. Kalnins et al., QUADRICS ON COMPLEX RIEMANNIAN SPACES OF CONSTANT CURVATURE, SEPARATION OF VARIABLES, AND THE GAUDIN MAGNET, Journal of mathematical physics, 35(4), 1994, pp. 1710-1731
Integrable systems that are connected with orthogonal separation of va
riables in complex Riemannian spaces of constant curvature are conside
red herein. An isomorphism with the hyperbolic Gaudin magnet, previous
ly pointed out by one of the authors, extends to coordinates of this t
ype. The complete classification of these separable coordinate systems
is provided by means of the corresponding L matrices for the Gaudin m
agnet. The limiting procedures (or epsilon calculus) which relate vari
ous degenerate orthogonal coordinate systems play a crucial role in th
e classification of all such systems.