  Fast and collisional flavor instabilities possibly occur in the neutrino
decoupling regions of core-collapse supernovae and neutron-star mergers. To
gain a better understanding of the relevant flavor dynamics, we numerically
solve for the collisionally unstable evolution in a homogeneous, anisotropic
model. In these calculations collisional instability is precipitated by unequal
neutrino and antineutrino scattering rates. We compare the solutions obtained
using neutral-current and charged-current interactions. We then study the
nonlinear development of fast instabilities subjected to asymmetric scattering
rates, finding evidence that the onset of collisional instability is hastened
by fast oscillations. We also discuss connections to other recent works on
collision-affected fast flavor conversion.
