  The discovery of the highly relativistic neutron star (NS) binary (in which
both NS's are pulsars) not only increases the estimated merging rate for the
two NS's by a large factor, but also adds the missing link in the double helium
star model of binary NS evolution. This model gives $\sim 20$ times more
gravitational merging of low-mass black-hole (LMBH), NS binaries than binary
NS's, whatever the rate for the latter is.
