Does anyone have an idea of what a Venn diagram is?
Basically, they are a way to visualize interactions between sets or groups. For simple ones, circles are generally used, although the more complicated ones may require more complex closed figures. They can also be used to help show whether syllogisms (i.e.: all x are y, all y are z, therefore all x are z) have valid conclusions or not. Since they are a visual representation, it is hard to explain them using text only. But here is a very simple diagram. If this is a chart of people with the left circle representing Women the right circle representing Redheads, then the intersection, A^B would be women who are redheads. A would be women who are not redheads and B would be people that are not women but are redheads (Opie would fit here :)) The area outside of the circles, U, would be people that are neither women or redheads (Mr T or George Bush). Again, this is a very simple diagram. More complex ones can have more circles or other shapes, circles within circles, etc. A good basic page a
