Metamath Proof Explorer
Description: 2 is not a limit ordinal. (Contributed by BTernaryTau, 1-Dec-2024)
(Proof shortened by RP, 13-Dec-2024)
|
|
Ref |
Expression |
|
Assertion |
nlim2NEW |
⊢ ¬ Lim 2o |
Proof
Step |
Hyp |
Ref |
Expression |
1 |
|
1on |
⊢ 1o ∈ On |
2 |
|
nlimsuc |
⊢ ( 1o ∈ On → ¬ Lim suc 1o ) |
3 |
|
df-2o |
⊢ 2o = suc 1o |
4 |
|
limeq |
⊢ ( 2o = suc 1o → ( Lim 2o ↔ Lim suc 1o ) ) |
5 |
3 4
|
ax-mp |
⊢ ( Lim 2o ↔ Lim suc 1o ) |
6 |
2 5
|
sylnibr |
⊢ ( 1o ∈ On → ¬ Lim 2o ) |
7 |
1 6
|
ax-mp |
⊢ ¬ Lim 2o |