This is pretty obvious, since you can easily count from one member to the next.
I’d just like to chip in that it isn’t necessary for a countably infinite set to have an obvious method of counting. Listing all of the rationals in numerical order isn’t possible (what’s the smallest fraction above 0?) but it is nevertheless possible to create a bijection with the naturals.
I’d just like to chip in that it isn’t necessary for a countably infinite set to have an obvious method of counting. Listing all of the rationals in numerical order isn’t possible (what’s the smallest fraction above 0?) but it is nevertheless possible to create a bijection with the naturals.
Great point! It’s been a while since my degree (and I don’t use it), so I knew I’d probably get something wrong.