Editing Venn diagram (section)

==={{anchor|Edwards-Venn|Adelaide|Hamilton|Massey|Victoria|Palmerston North|Manawatu}}Edwards–Venn diagrams===
<gallery widths="150px" class="skin-invert-image">
Image:Venn-three.svg| Three sets
Image:Edwards-Venn-four.svg| Four sets
Image:Edwards-Venn-five.svg| Five sets
Image:Edwards-Venn-six.svg| Six sets
</gallery>
[[Anthony William Fairbank Edwards]] constructed a series of Venn diagrams for higher numbers of sets by segmenting the surface of a sphere, which became known as Edwards–Venn diagrams.<ref name="Edwards_2004"/> For example, three sets can be easily represented by taking three hemispheres of the sphere at right angles (''x''&nbsp;=&nbsp;0, ''y''&nbsp;=&nbsp;0 and ''z''&nbsp;=&nbsp;0). A fourth set can be added to the representation, by taking a curve similar to the seam on a tennis ball, which winds up and down around the equator, and so on. The resulting sets can then be projected back to a plane, to give ''cogwheel'' diagrams with increasing numbers of teeth—as shown here. These diagrams were devised while designing a [[stained-glass]] window in memory of Venn.<ref name="Edwards_2004"/>