Depends how you define proof. Can you ever say with 100% certainty something doesn't exist? No. Can you prove it beyond a reasonable doubt? Yes. I mean I'm assuming most people here would agree Santa isn't real (sorry if I'm bursting a bubble) but no you can't absolutely prove he isn't.I postulate that the question "You guys are "real" aren't you?" is potentially unanswerable.
I has been (imo, very well!) pointed out, "I drink, therefore I am" as a valid proof of one's existence.
Whereas proving oneself is not real is much harder. As I have heard Rick Gervais point out, "you can not prove something does not exist"...or something to that effect.
PS...and yeah, 5 pages is nothin' ;-)
You also can't 100% prove something is real. Cogito, ergo sum might have helped Descartes sleep at night but can you be 100% that we aren't all part of a complex simulation and that our thoughts aren't just subroutines within our program?
Yeah I think we'll hit 5 easy...