First I'll start out with this is not a homework assignment.

So we are going over graphs and I am trying to understand where some of this is used in computer programming. Keep in mind this is non-visual.

This is basica algebra.

Intersection is when two sets of data (elements of the set) containing some data that is both sets.
Example
Set A = {10,20,30,40}
Set B = {11,20,30,51}

In this case the numbers 20 and 30 are in both sets. Therefore these two sets intersect.

This is also an example of union. In a union all the data (or elements of the sets) that are in Set A and Set B. So all the numbers 10,11,20,30,40,51 belong to this union.

What I am trying to understand is how is this used in a non visual program. I know the book says it is used for project managment, electrical circuits but really does not go into how or show what you use it for when you use graphs and use intersection, subsets, union, etc, etc.

Just elements to me. Could be used for a lot things in a program or maybe I am look at this wrong.

BTW - the homework is outputting the nodes of a graph in a depth first traveral.

Thank you very much.