So let's state another example, a simple one, straight-forward, but just to highlight the relationship when we have a start-to-start relationship. So let's say we have a project of three activities only Activity x, activity y, activity z. With a duration of 9. Duration of 4, and duration of 2. And we set the example to go through a start-to-start, so let's say, the relationship is as following. To start relation between activity x and y, and the start-to-start relationship between activity y and z. In that aspect, we want to do the forward and the backward pass calculations. The forward pass because all the projects has the relationship between a start-to-start, they all would be starting at the same time. So let's say, if we have an early start of 0 here, 0+9, which will be equal the early finish date of activity x. And when we want to calculate the early start date of activity y, the relationship with its predecessor is s-to-s. So 0, it will go here as 0. 0+4, the early finish date for activity y is 4. And then we have also a start-to-start relationship with z and y, which will take this as 0+2 = 2. So when we do that backward, past calculations, because the duration of the project will finish when activities with the longest duration will finish. So in this case, we have the simple three activities. The longest duration is 9. Then we can take the 9 here. As the late finish date for activity x and the late start date will be 0 for activity x. So the following activity will be also as well as y and z will finish towards the end of the project, because this is only the relationship between these three activities. In this case you have a late finish of 9 and 9 for both y and z, which will make it the late start date for z = 7 and the late start date for y = 5. So this, which we'll cover it later, it consider as a critical activity we can, we have to start when the beginning of the project starts and finish at 9. But activity y and z, we still have a leeway, or a buffer time, to delay the start of any of these activities and start as late as day number 5, as late as day number 7. And still the latest time to finish has to be on 9, to make sure that the entire project will not be extended more that 9 days. So let's say we have the same Simple three activities of x. Y. And z. The same durations of 9, 4, and 2. And it will have also, the start-to-start relationships, between these three activities. The only addition I'm going to give here, is I'm going to assume we have the 6 days lag time between x and y. And only 1 day lag time between activity y and z. How that will affect our calculations from the forward and the backward pass calculation? Form the forward pass we start the first activity of the project. Early start 0+9 =9, the early finish of activity x. And the early start of activity y will be 0+6 = 6. That will lead us to have an early finish date for activity y = 6+4 = 10. So that early start moving forward in the calculations, the early start date for activity z will be 6 + 1 because of the start-to-start relationship, 6+1 = 7, and the early finish date will be 9. So with that being said, instead of having the duration of the project of 9 days, we extended it to ten days because of this restriction here. So in this case, the controlled day we have for activity y will be 10. Which will be the same for the other two activities. However, that late start date for all three will be just the late finish minus the duration of 1, 6, and 8. So that's the simple stuff to start relationships between three activities with lag of 6 days and 1 day.
