4 ms·
My argument aws: The constructible numbers are not "complete". You can always find cauchy sequences of constructible numbers that do not converge to a construct
by heinrichhartman 10y ago
My argument aws: The constructible numbers are not "complete". You can always find cauchy sequences of constructible numbers that do not converge to a constructible number.
If you add the requirement that the sequence itself must be constructible things _might_ change. It depends on how you define constructible sequence.
I thought Cantors argument would show that there are uncountable constructible sequences:
- Assume there are countable many C[1], C[2]
- Construct a new one D = C[1][1] + 1, C[2][2] + 1, ...
- D in constructible, hence it's on the list: C[j] = D
- But D[j] =/= C[j][j]
- Contradiction.
This proof is however not correct. The sequence D does not need to be constructible.