“…This relation has been rediscovered and generalized by Arnold and Vassiliev [1,2] in 1989 and quite simultaneously by Hojman et al [17]. In fact the generalization of Kasner's result had already been obtained by Collas [5] and implicitly enters into the frame of the coupling constant metamorphosis of Hietarinta et al [16,31,37]. Even if we restrict ourselves to the classical aspects (the study of this correspondence in the quantum mechanical frame has an interesting parallel history that we do not deal with here), numerous articles have been published on this subject during the last fifteen years [13,15,24,25,35,36,38].…”