- 349 名前：１３２人目の素数さん mailto:sage [2021/10/17(日) 10:19:16.86 ID:dQP0ifDN.net]
- >>321
つづき
Successors are used to define the usual set-theoretic encoding of the natural numbers. In this encoding, zero is the empty set:
0 = {}.
The number 1 is the successor of 0:
1 = 0 ∪ {0} = {} ∪ {0} = {0} = {{}}.
Likewise, 2 is the successor of 1:
2 = 1 ∪ {1} = {0} ∪ {1} = {0,1} = { {}, {{}} },
and so on:
3 = {0,1,2} = { {}, {{}}, {{}, {{}}} };
4 = {0,1,2,3} = { {}, {{}}, { {}, {{}} }, { {}, {{}}, {{}, {{}}} } }.
A
