Open communicating class
= Open communicating class
A <communicating class> of a <Markov chain> is open when a state in the class has positive probability of transitioning to a state outside it. Once a path leaves, it cannot return to the class: a return path would make the outside state communicate with the class. Every open class consists of <transient states>. Conversely, a finite transient <communicating class> is open; an infinite <closed communicating class> can be transient.