“…The theorem above is a generalization of, and was motivated by, a classical result of Hartogs [Ran,II.5], asserting (in modern language) that a domain U in D n × C of the form (Hartogs tube) U = { (z, w) | |w| < e −f (z) }, where f : D n → [−∞, +∞) is an upper semicontinuous function, is Stein if and only if f is plurisubharmonic. Indeed, in this special case the Poincaré metric is easily computed, and one checks that the plurisubharmonicity of f is equivalent to the plurisubharmonic variation of the fiberwise Poincaré metric.…”