In the Proof of Theorem 4.4 on page 164 the assumption is stated that the sequence of classes chosen by the greedy algorithm is sorted by starting time. Isn't more natural that they should be sorted by finish time, as that is how they are output from the algorithm? It is also easier to argue that that we can use gj instead of cj in the modified schedule S'.
In the Proof of Theorem 4.4 on page 164 the assumption is stated that the sequence of classes chosen by the greedy algorithm is sorted by starting time. Isn't more natural that they should be sorted by finish time, as that is how they are output from the algorithm? It is also easier to argue that that we can use gj instead of cj in the modified schedule S'.