vers taking the appropriate value

    In addition, a time-reverse trap space (trmaxts) describes a region that,
    once exited, cannot be reentered. Thus, if the LDOI of the region contains
    any contradiciton, the region cannot contain any attractor. Therefore,
    we include a third criterion for the rspace:

    3) is not in a state belonging to an attractor-free time-reversed trap space

    The return value is a list L of lists of prime implicants. Each element of L
    is to be interpreted as a li