Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 1 00:00:00,980 --> 00:00:03,003 First, some definitions. 2 2 00:00:04,160 --> 00:00:07,200 There are four kinds of precedence links you can use, 3 3 00:00:07,200 --> 00:00:09,500 but only the finish to start link is practical 4 4 00:00:09,500 --> 00:00:11,653 in the vast majority of situations. 5 5 00:00:13,070 --> 00:00:14,993 So first, finish to start. 6 6 00:00:16,290 --> 00:00:18,350 The predecessor must finish 7 7 00:00:18,350 --> 00:00:20,343 and then the successor can start. 8 8 00:00:21,840 --> 00:00:24,790 It's shown with an arrow from the end of the predecessor 9 9 00:00:24,790 --> 00:00:26,623 to the start of the successor. 10 10 00:00:27,650 --> 00:00:31,063 These will suffice for almost all uses in most projects. 11 11 00:00:32,080 --> 00:00:34,690 However, for completeness, let's look at the others. 12 12 00:00:34,690 --> 00:00:36,560 In case you ever find an unusual situation 13 13 00:00:36,560 --> 00:00:38,260 where you want to use one of them. 14 14 00:00:39,110 --> 00:00:40,770 There's finish to finish 15 15 00:00:40,770 --> 00:00:43,270 where the successor must finish 16 16 00:00:43,270 --> 00:00:45,463 at the same time as the predecessor. 17 17 00:00:46,472 --> 00:00:49,140 The arrow goes from the end of the predecessor 18 18 00:00:49,140 --> 00:00:51,133 to the end of the successor. 19 19 00:00:52,183 --> 00:00:54,230 Then there's start to start 20 20 00:00:54,230 --> 00:00:57,070 where the successor must start 21 21 00:00:57,070 --> 00:00:59,123 at the same time as the predecessor. 22 22 00:00:59,967 --> 00:01:03,110 The arrow goes from the beginning of the predecessor 23 23 00:01:03,110 --> 00:01:05,013 to the beginning of the successor. 24 24 00:01:06,190 --> 00:01:07,200 And then finally, 25 25 00:01:07,200 --> 00:01:08,930 there's start to finish 26 26 00:01:08,930 --> 00:01:12,443 where the successor must finish when the predecessor starts. 27 27 00:01:13,525 --> 00:01:16,470 The arrow goes from the beginning of the predecessor 28 28 00:01:16,470 --> 00:01:18,353 to the end of the successor. 29 29 00:01:19,431 --> 00:01:21,927 If these last three seem a bit mind bending, 30 30 00:01:21,927 --> 00:01:23,690 that's normal. 31 31 00:01:23,690 --> 00:01:27,010 You can use them and enter them in the Gantt Chart tool, 32 32 00:01:27,010 --> 00:01:29,360 but in practice you usually structure your project 33 33 00:01:29,360 --> 00:01:31,540 to use only finish to start, 34 34 00:01:31,540 --> 00:01:35,630 which is by far preferable since it's so human intuitive. 35 35 00:01:35,630 --> 00:01:38,070 And that's the main purpose of the precedence diagram, 36 36 00:01:38,070 --> 00:01:40,083 to communicate with people. 37 37 00:01:40,922 --> 00:01:43,570 We'll only use the finish to start links 38 38 00:01:43,570 --> 00:01:44,870 in the rest of the course. 39 39 00:01:46,750 --> 00:01:48,770 You can also use finish to start links 40 40 00:01:48,770 --> 00:01:51,150 to show leads and lags, 41 41 00:01:51,150 --> 00:01:53,990 usually when entering them into the Gantt chart tool. 42 42 00:01:53,990 --> 00:01:55,240 See the schedule section. 43 43 00:01:56,710 --> 00:02:01,380 For leads, you can show overlapping deliverables 44 44 00:02:01,380 --> 00:02:03,110 where the successor starts 45 45 00:02:03,110 --> 00:02:06,170 a bit before the predecessor finishes. 46 46 00:02:06,170 --> 00:02:08,670 Typically used only to show fast tracking, 47 47 00:02:08,670 --> 00:02:11,320 as we'll cover in the Monitoring and Control section. 48 48 00:02:12,220 --> 00:02:13,820 They're specified in the Gantt chart tool 49 49 00:02:13,820 --> 00:02:16,720 with notation like FS minus 5d 50 50 00:02:16,720 --> 00:02:20,253 for Finish to Start minus five days. 51 51 00:02:21,810 --> 00:02:25,090 Here's an example where the successor starts five days 52 52 00:02:25,090 --> 00:02:26,840 before the predecessor is finished. 53 53 00:02:28,600 --> 00:02:33,330 Then you've got lags to show a delay between deliverables, 54 54 00:02:33,330 --> 00:02:35,853 typically used for empty waiting time. 55 55 00:02:37,210 --> 00:02:38,750 They're specified in the Gantt chart tool 56 56 00:02:38,750 --> 00:02:41,120 with notation like FS plus 10d 57 57 00:02:41,120 --> 00:02:43,513 for Finish to Start plus 10 days. 58 58 00:02:44,570 --> 00:02:46,750 Here's an example where the successor starts 59 59 00:02:46,750 --> 00:02:49,363 10 days after the predecessor finishes. 60 60 00:02:50,440 --> 00:02:53,960 However, as described earlier in the WBS section, 61 61 00:02:53,960 --> 00:02:55,790 if the delay between two deliverables 62 62 00:02:55,790 --> 00:02:57,880 is caused by an external event, 63 63 00:02:57,880 --> 00:03:00,010 it is usually better to actually show the delay 64 64 00:03:00,010 --> 00:03:03,223 as a separate deliverable to highlight its visibility. 5483