"A non-existent amount of mathematics" -- which the joke could have been interpreted as implying -- is not zero mathematics: that would be an existent amount.

"A non-existent amount of mathematics" -- which the joke could have been interpreted as implying -- is not zero mathematics: that would be an existent amount. Another place these semantics arise is in talk about probability and possibility, wherein the possible can have zero probability (e.g. any specific value in a continuous probability distribution), but the impossible cannot have a zero probability because by definition it is outside the set of "possible events" (measure theoretically). Both make little intuitive sense.