  We report on the last four editions of the reactive synthesis competition
(SYNTCOMP 2018-2021). We briefly describe the evaluation scheme and the
experimental setup of SYNTCOMP. Then, we introduce new benchmark classes that
have been added to the SYNTCOMP library and give an overview of the
participants of SYNTCOMP. Finally, we present and analyze the results of our
experimental evaluations, including a ranking of tools with respect to quantity
and quality - that is, the total size in terms of logic and memory elements -
of solutions.
