def Dequiv(fsm, states, agents):
    """
    Return the set of fsm that equivalent to states w.r.t. distributed
    knowledge of agents.
    
    fsm -- a MAS representing the system
    states -- a BDD representing a set of states of fsm
    agents -- a set of agents names of fsm.
    """
    return fsm.equivalent_states(states, frozenset({agents}))
