Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 1 00:00:01,270 --> 00:00:03,010 Let's take a look at how the critical path is 2 2 00:00:03,010 --> 00:00:06,520 actually calculated by the Gantt chart tool. 3 3 00:00:06,520 --> 00:00:08,810 If you understand this, you will understand 4 4 00:00:08,810 --> 00:00:11,310 the critical path in your bones, 5 5 00:00:11,310 --> 00:00:15,382 much better than most people who simply know it's important. 6 6 00:00:15,382 --> 00:00:17,881 We'll put the explanation together in pieces, 7 7 00:00:17,881 --> 00:00:21,740 and each piece might not make complete sense by itself, 8 8 00:00:21,740 --> 00:00:22,693 so stay with me. 9 9 00:00:23,550 --> 00:00:25,590 We'll run through an example and it should all 10 10 00:00:25,590 --> 00:00:27,599 come together by the end. 11 11 00:00:27,599 --> 00:00:32,100 First, we perform a forward pass, 12 12 00:00:32,100 --> 00:00:35,520 scanning the project from the beginning to the end 13 13 00:00:35,520 --> 00:00:39,902 to determine each deliverable's earliest start, ES, 14 14 00:00:39,902 --> 00:00:44,010 and earliest finish, EF, given the constraints 15 15 00:00:44,010 --> 00:00:45,709 of the project logic. 16 16 00:00:45,709 --> 00:00:49,965 To do this, we'll copy the predecessor's greatest 17 17 00:00:49,965 --> 00:00:54,470 earliest finish to the successor's earliest start 18 18 00:00:55,478 --> 00:00:59,360 and then we'll add the earliest start and the duration 19 19 00:00:59,360 --> 00:01:01,323 to get the deliverable's earliest finish. 20 20 00:01:02,719 --> 00:01:05,290 To keep track we'll record the earliest start 21 21 00:01:05,290 --> 00:01:07,700 in the top left of the deliverable 22 22 00:01:07,700 --> 00:01:10,913 and the earliest finish on the top right of the deliverable. 23 23 00:01:12,336 --> 00:01:16,350 Then, we'll perform a backward pass, 24 24 00:01:16,350 --> 00:01:20,000 scanning the project from the end back to the beginning 25 25 00:01:20,000 --> 00:01:24,180 to determine each deliverable's latest start, LS, 26 26 00:01:24,180 --> 00:01:27,640 and latest finish, LF, Given the constraints 27 27 00:01:27,640 --> 00:01:29,490 of the project logic. 28 28 00:01:29,490 --> 00:01:34,490 To do this, we'll copy the successor's least latest start 29 29 00:01:35,960 --> 00:01:38,060 to the predecessor's latest finish 30 30 00:01:38,898 --> 00:01:41,840 and then we'll subtract the latest finish 31 31 00:01:41,840 --> 00:01:45,723 minus the duration to get the deliverable's latest start. 32 32 00:01:47,820 --> 00:01:50,590 To keep track, we'll record the latest finish in the 33 33 00:01:50,590 --> 00:01:53,700 bottom right of the deliverable and the latest start 34 34 00:01:53,700 --> 00:01:55,823 on the bottom left of the deliverable. 35 35 00:01:57,163 --> 00:02:01,100 Now, notice how the words for the forward pass 36 36 00:02:01,100 --> 00:02:03,090 are all positive sounding? 37 37 00:02:03,090 --> 00:02:06,363 Forward, greatest, add. 38 38 00:02:07,278 --> 00:02:09,160 And the words for the backward pass 39 39 00:02:09,160 --> 00:02:11,250 are all negative sounding? 40 40 00:02:11,250 --> 00:02:15,570 Backward, least, subtract. 41 41 00:02:15,570 --> 00:02:17,800 This is just a coincidence, 42 42 00:02:17,800 --> 00:02:20,023 but it makes it a bit easier to remember. 43 43 00:02:22,680 --> 00:02:26,350 And then, we calculate each deliverable's float 44 44 00:02:26,350 --> 00:02:30,209 by the difference between the forward pass and backward pass 45 45 00:02:30,209 --> 00:02:33,770 by subtracting the deliverable's earliest finish 46 46 00:02:33,770 --> 00:02:36,853 from the late finish to see if the numbers are different. 47 47 00:02:38,260 --> 00:02:41,660 If so, it indicates that the project logic can let the 48 48 00:02:41,660 --> 00:02:45,053 deliverable float a bit without impacting the critical path. 49 49 00:02:46,290 --> 00:02:49,240 We'll write the float on the top middle of the deliverable. 50 50 00:02:50,195 --> 00:02:52,874 The deliverables where the float is zero, 51 51 00:02:52,874 --> 00:02:54,860 where the earliest finish and latest finish 52 52 00:02:54,860 --> 00:02:58,523 are exactly the same, are on the critical path. 53 53 00:02:59,517 --> 00:03:03,113 Now, let's look at an example. 4756