We have 65 work assignments and must randomly re-assign them to our
employees each month. We have given each work assignment a number 1-65.
How do we randomly re-shuffle a list of 45 whole numbers at the beginning of
each month?

Once we have learned how to perform the random re-shuffle above, we would
also like to learn how to tailor the random assignments as follows:

First, how do we prevent an employee from being re-assigned the same
assignment they performed last month or perhaps the last 3 months?

Second, how do we prevent employees from receiving certain random numbers
that represent tasks they are not capable of performing? In other words,
how do we prohibit an employee from being assigned a subset of certain tasks
(task numbers) included in the comprehensive list of tasks?

Thank you for any help with this question.