From what I have understood reading the UCT paper Bandit based monte-carlo planning, by Levente Kocsis and Csaba Szepesvári, MCTS/UCT requires a generative model.
Does it mean that, in case there is no generative model of the environment, we cannot use MCTS?
If we can still use MCTS, how does the roll-out happen in this case, as there is no simulation?