City of New York was building a new civic center and had a deadline to get a hugh event. They had a contractor doing the work with 60 days to finish. The city's police union was in negotiations with the city and the union wasn't happy with the progress. The union sent a picket line to stop delivery of materials to the worksite. Police officers were supposed to be making sure nothing was held up at the site. What is the principal-agent problem with this? Also, is it a hold up problem for the city or another problem?