Analytical and numerical results on equilibrium configurations of rotating
fluid bodies within Einstein's theory of gravitation are reviewed. Particular
emphasis is placed on continuous parametric transitions to black holes. In this
connection the uniqueness of extremal Kerr black holes is discussed.Comment: 3 pages, talk given at the Twelfth Marcel Grossmann Meeting (Paris,
July 12 - 18, 2009), submitted to the Conference Proceedings, v3: references
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