Studies of Euler diagrams/legato

This is one of the two 4-ary Boolean functions that have a multicrossing of all sets &mdash; the other being. It has all possible spots except the intersection of no sets and of all sets. (Like in two dimensions.)

As a sphere surface the Euler diagram has 6 square and 8 triangle cells, forming a spherical. (So its graph forms a .) The squares have weight 2. Eeach square borders two triangles with weight 1 and two with weight 3.