Retorts

Venn Diagrams

It is a pity that Venn Diagrams are not used for representing the intersection of four (more than three) sets. [Neurobics, October 1993]

Four oranges can be stacked in a tetrahedral arrangement, with the fourth orange sitting on a base of three touching oranges. If the oranges are pushed into each other, then the bruised regions can represent the various intersections of four sets among themselves.

D.S. McDonald, Wellington