Given a Kripke structure $K$ and an $ACTL$ formula $\phi$ you can attest that it's false by finding a counterexample, more precisely a path, eventually followed by a loop.
Is there an equivalent concept of counterexample for an $ACTL^*$ formula? If it exists, what form does it have? Is it a path, a tree, or what else?
Does something change if the structure $K$ is finite?