Before revision:  Consequently, the expected sojourn time of non-purging (n,k) fork-join queues can be approximated with the help of existing approximations for basic fork-join queues. Then, approximations for non-purging queues are used to improve the upper bounds for purging (n,k) fork-join queues.
After revision:  Consequently, the expected sojourn time of non-purging (n,k) fork-join queues . The uncovered approximations are then used to improve the upper bounds for purging (n,k) fork-join queues.