The Worker Adjustment and Retraining Notification Act (WARN) requires employers with 100 or more employees to provide notification 60 calendar days in advance of plant closings and mass layoffs. Advance notice gives workers and their families transition time to adjust to the prospective loss of employment, seek other jobs, or get necessary training. Some employers complain that WARN reduces necessary flexibility and makes them reluctant to open new production facilities. How are barriers to entry and exit similar? How are they different?