throughout the evolution for some initial data) is stable against small changes in the equation of state.

Hence, if dust admits a naked singularity for some initial data, a naked singularity will form also in the collapse of a fluid for which the ratio of pressure to density is small but non-zero, provided one starts from the same initial data. It may be possible to generalise these results, by using the Raychaudhri equation to predict which initial conditions lead to a black hole, and which ones to naked singularities. This is at present under investigation.

Non-spherical Gravitational Collapse
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Amongst the very few studies of non-spherical collapse that have been carried out so far is the numerical work of Shapiro and Teukolsky on oblate and prolate collisionless spheroids. Since there really have been no recent developments in this direction, I refer the reader to the discussion of their work in Section 3 of my earlier review [@tps], and to the review by Wald [@revi].

A recent work on non-spherical perturbations of spherical collapse deserves mention. Iguchi et al. have shown that the naked singularities arising in spherical dust collapse are marginally stable against odd-parity non-spherical gravitational wave perturbations [@ig].

Unlike 