G ra v itatio n al waves in general re la tiv ity X IV . B ondi expansions an d th e 'p o ly h o m o g en eity ' of J? The structure of poly homogeneous space-times (i.e. space-times with metrics which admit an expansion in terms of r~J log* r) constructed by a Bondi-Sachs type method is analysed. The occurrence of some log terms in an asymptotic expan sion of the metric is related to the non-vanishing of the Weyl tensor at J 1 . The validity in this more general context of various results from

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... the standard treat ment of J , including the Bondi mass loss formula, the peeling-off of the Riemann tensor and the Newman-Penrose constants of motion, is considered. P. T.