The undecidability of the theory of immediate pairs of Henselian valued fields

Universality for deterministic Timed Büchi Automata (TBA) is PSPACE-complete but becomes highly undecidable when unrestricted nondeterminism is allowed. More precisely, universality for nondeterministic TBA is Π$^1_1$-hard and its precise position in ...

Universality for deterministic Timed Büchi Automata (TBA) is PSPACE-complete but becomes highly undecidable when unrestricted nondeterminism is allowed. More precisely, universality for nondeterministic TBA is Π^1_1-hard and its precise position in the ...

In this work, we study decision problems related to timed automata with silent transitions (TA$_{ε}$) which strictly extend the expressiveness of timed automata (TA). We first answer negatively a central question raised by the introduction of silent ...