We present a general coalgebraic setting in which we define finite and infinite behaviour with B\"uchi acceptance condition for systems whose type is a monad. The first part of the paper is devoted to presenting a construction of a monad suitable for modelling (in)finite behaviour. The second part of the paper focuses on presenting the concepts of a (coalgebraic) automaton and its ($\omega$-) behaviour. We end the paper with coalgebraic Kleene-type theorems for ($\omega$-) regular input. The framework is instantiated on non-deterministic (B\"uchi) automata, tree automata and probabilistic automata.

@article{paperbot1252,
  title = {A coalgebraic take on regular and $\omega$-regular behaviours},
  author = {Tomasz Brengos},
  journal = {Logical Methods in Computer Science},
  volume = {Volume 17, Issue 4},
  year = {2021},
  doi = {10.46298/lmcs-17(4:24)2021}
}