One construction of the natural numbers that I've seen is
1. There exists an element 0 that is a natural number
2. For every natural number there is a "sucessor" that is also a natural number. (i.e. if n is a natural number then n+1 is a natural number)
This construction means there can't be an upper bound N because then step 2 couldn't be applied to N.
Maybe there are other constructions that could workaround this? I'm guessing not because you'd still struggle to define the usual rules of addition for all numbers in a bounded set
1. There exists an element 0 that is a natural number
2. For every natural number there is a "sucessor" that is also a natural number. (i.e. if n is a natural number then n+1 is a natural number)
This construction means there can't be an upper bound N because then step 2 couldn't be applied to N.
Maybe there are other constructions that could workaround this? I'm guessing not because you'd still struggle to define the usual rules of addition for all numbers in a bounded set