@Homomorph,
Hi Homomorph,
Nice to meet you. Let me get this right - "Something" > let's call it "Brian" is in set A. Every other "something" > let's call it "Diane" > is in B. Brian and Diane are on alternate worlds. There is no X let's call it "Fido" and "Fido" who doesn't exist is on Brian's world AND Diane's world (which cannot share elements (so "Fido" isn't on Brian or Diane's worlds, but is, and doesn't exist). And we're leaving it at that for now, because you're not sure where to go with it yet. And the IDEA of something 'Not existing' Exists. And to sum up, we determine that the only way to define something that doesn't exist is to just say that it doesn't exist.
My reply to this is... Could I get that with a side-order of crocodile, please?
When you have decided where to go with this, please let me know. I (and I mean this) think you are completely my type of person. And I'm going to adore you being here on the forum.
We'll likely have to do some work on the math though.
Thank you Homomorph. Have a fantastic evening.
Mark...