Well, it is probably zero but (It is not) someone else should give their thoughts on the matter.
DavidQD you are on the forum - what do you think?
I would say it is "aleph null" or undefined, unless the infinities are explicitly defined as countable, but I'll ask Georg Cantor.
On first blush, we might consider the answer to be "0.'
But, it's not.....
Consider the set of integers on the number line. You will agree - I hope - that this set is infinite. Now, consider the set of even integers on the number line. Again, we'll consider this set to be infinite, too.
So, subtracting the second "infinity" from the first "infinity," we end up with another infinite set - the set of all odd integers !!
Thus, ∞ - ∞ = ∞
Also, notice another odd property......I've divided one set in half and gotten another infinite set. Thus....
∞ / 2 = ∞
One more interesting idea, and then I'll shut up. Which "infinity" is "greater?" The set of all positive integers, or the set of all positive even integers??
Note, that I can "count" each positive even integer.....For example, 2 is the first one, 4 is the second one, etc. Thus, I can put each positive even integer into a one-to-one correspondence with a "counting" number. And since I can do so, then the set of positive even integers must be just as large as the set of all the positive integers !!!
There is a post on here titled
A Method of Statistical Inference on Two-dimensional Object Ratios
It broaches infinities – it is a brilliant peace of work.
Thanks Chris and David and thank you Anana for you good manners.
If you give the answers you like a thumbs up you can give them lots of points! You have the POWER!
It's right there in my eighth "sentence".......
"Thus, ∞ - ∞ = ∞"..........
I thought you might be able to argue different cases to get different answers and hence end up with undefined.