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Higher-order Venn diagrams | Quentin Stafford-Fraser and Rose Melikan - http://qandr.org/quentin/software/venn
"But how do you represent four different sets? Try drawing it, and you'll realise it's quite tricky to come up with something that shows all 16 possible regions." ‎- ati
looks like Venn puzzle ‎- волна бургерных