Black Holes, Supernovae and Gamma Ray Bursts
  We review recent progress in our understanding of the nature of gamma ray
bursts (GRBs) and in particular, of the relationship between short GRBs and
long GRBs. The first example of a short GRB is described. The coincidental
occurrence of a GRB with a supernova (SN) is explained within the induced
gravitational collapse (IGC) paradigm, following the sequence: 1) an initial
binary system consists of a compact carbon-oxygen (CO) core star and a neutron
star (NS); 2) the CO core explodes as a SN, and part of the SN ejecta accretes
onto the NS which reaches its critical mass and collapses to a black hole (BH)
giving rise to a GRB; 3) a new NS is generated by the SN as a remnant. The
observational consequences of this scenario are outlined.
