“…To the best of our knowledge, however, there are no previous results on a posteriori error bounds for implicit-explicit high order fully-discrete methods involving dG-timestepping for nonlinear evolution PDEs. This is in contrast with the increasing number of interesting works on a posteriori error analyses for low order time-stepping schemes for nonlinear evolution problems; see, e.g., [8,10,12,17,36,52] and the references therein. At the same time, there exist only few works on the a posteriori error analysis of high order time-stepping schemes for time-discrete nonlinear parabolic problems [30,33,34,41,46].…”