Studies of Euler diagrams/farofe

This Boolean function has 12 of 16 true spots. It is similar to Studies of Euler diagrams/medusa, but without spot 3. (See here.)

symmetry
The Euler diagrams shown above are not good, because they hide the symmetry of this Boolean function.




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filtrates
Each of the 6 pairs is a 2-split (with all 4 quadrants). Only one of the 4 triples is a 3-split (with all 8 octants).