4.1 Given the unit data in Table 4.8 and Table 4.9, use forward DP to find the optimum unit commitment schedules covering the 8-h period. Table 4.9 gives all the combinations you need, as well as the operating cost for each at the loads in the load data. A "x" indicates that a combination cannot supply the load. The starting conditions are as follows: at the beginning of the first period, units 1 and 2 are up and units 3 and 4 are down and have been down for 8 h. 4.1 Given the unit data in Table 4.8 and Table 4.9, use forward DP to find the optimum unit commitment schedules covering the 8-h period. Table 4.9 gives all the combinations you need, as well as the operating cost for each at the loads in the load data. A "x" indicates that a combination cannot supply the load. The starting conditions are as follows: at the beginning of the first period, units 1 and 2 are up and units 3 and 4 are down and have been down for 8 h