Universal Coalgebra provides the notion of a coalgebra as the natural mathematical generalization of state-based evolving systems such as (infinite) words, trees, and transition s...
We prove that tree isomorphism is not expressible in the language (FO + TC + COUNT). This is surprising since in the presence of ordering the language captures NL, whereas tree is...
Partially observed actions are observations of action executions in which we are uncertain about the identity of objects, agents, or locations involved in the actions (e.g., we kn...
We consider formulas which, in addition to the symbols in the vocabulary, may use two designated symbols ≺ and + that must be interpreted as a linear order and its associated ad...
Alternating timed automata are a powerful extension of classical Alur-Dill timed automata that are closed under all Boolean operations. They have played a key role, among others, ...