  In this paper, we study inverse boundary problems associated with semilinear
parabolic systems in several scenarios where both the nonlinearities and the
initial data can be unknown. We establish several simultaneous recovery results
showing that the passive or active boundary Dirichlet-to-Neumann operators can
uniquely recover both of the unknowns, even stably in a certain case. It turns
out that the nonlinearities play a critical role in deriving these recovery
results. If the nonlinear term belongs to a general $C^1$ class but fulfilling
a certain growth condition, the recovery results are established by the control
approach via Carleman estimates. If the nonlinear term belongs to an analytic
class, the recovery results are established through successive linearization in
combination with special CGO (Complex Geometrical Optics) solutions for the
parabolic system.
