Alpaga is the first tool for solving a problem as general as parity games of imperfect information. As a consequence, we can not compare the performances of Alpaga with any existing implementation, although we have a good confidence in its efficiency, thanks to the use of symbolic representations of sets of states through binary decision diagrams and the use of antichains in the computation.

Nevertheless, we plan to implement more naive approaches to solve parity games of imperfect information, for example by representing the set of states explicitly or by turning off the use of antichains (and thus working on the lattice of subset of states, instead of the lattice of antichains). We shall then be able to verify the efficiency gain hopefully brought by the use of antichains. Note that we are confident of the usefulness of antichains thanks to previous experimentations on the simpler problem of deciding universality of timed automata (see the following article). To be continued ...