  Timed automata are a convenient mathematical model for modelling and
reasoning about real-time systems. While they provide a powerful way of
representing timing aspects of such systems, timed automata assume arbitrary
precision and zero-delay actions; in particular, a state might be declared
reachable in a timed automaton, but impossible to reach in the physical system
it models. In this paper, we consider permissive strategies as a way to
overcome this problem: such strategies propose intervals of delays instead of
single delays, and aim at reaching a target state whichever delay actually
takes place. We develop an algorithm for computing the optimal permissiveness
(and an associated maximally-permissive strategy) in acyclic timed automata and
games.
