User blog comment:Eners49/The secret 0th hyper-operator?/@comment-2601:142:2:EC49:A496:CA1D:3DA2:B5DD-20180728144329/@comment-2601:142:2:EC49:A496:CA1D:3DA2:B5DD-20180728144933

You can use this logic to prove that 1?1 can be basically anything you want it to be, and that the empty set equals 2. Because that makes sense.