… languages, where a so called monitor checks whether or not a consecutive sequence of
observed system actions belongs to a formally specified language… of A is decidable in PSpace if …

… For instance, we can mention their application for the description of subclasses of the
context-free languages class with the decidable equivalence problem. For infinite iterations of finite …

… We intend to introduce here a new method for proving high undecidability results which
seems to be unexplored. It was actually noticed by Harel in [Har86] that “one can define Σ1 …

… By contrast, the first two classes are definable by fully decidable formalisms from temporal
… omega $-regular languages\/} and the {\em timed counter-free $\omega $-regular languages…

… of (Rk; ≤CA) is decidable. The question may be also asked … (L0)k; ≤CA)) is decidable
because, by a main fact in [Wag79]… of any ordinal is known to be decidable. It turns out that for k …

… We first restate some previous undecidability results. Then we prove that there are !-CFL in
… undecidability results about the topological complexity of omega context-free languages. …

… limit-stable languages. Moreover, we showed that this class of languages is a decidable,
proper subclass of finite recognizable trace languages. We proved how every recognizable …

… is decidable; that is, we show that it is decidable whether a … line on learning of omega-regular
languages; a first step in this … further development of nominal omega-regular languages [8]…

… fragment of regular languages, which is decidable. • Finally, … ’s complete axiomatisation of
omega-regular languages [17] is … algebras are sound for omegaregular languages as well. …

… -languages that are definable by fully decidable formalisms. The omega-regular languages
… finite counting, we dub them the timed omega-regular languages and the timed counter-free …