On the global visibility of a singularity in spherically symmetric   gravitational collapse
  We revisit the gravitational collapse of spherically symmetric Lema\^itre - Tolman - Bondi (LTB) dust models. A sufficient condition for global visibility of singularity is given. This condition also allows us to extend the condition of local visibility to mass functions which are not Taylor expandable near the centre. 
Sanjay Jhingan and Sahal Kaushik
gr-qc