Step |
Hyp |
Ref |
Expression |
1 |
|
pinn |
⊢ ( 𝐴 ∈ N → 𝐴 ∈ ω ) |
2 |
|
pinn |
⊢ ( 𝐵 ∈ N → 𝐵 ∈ ω ) |
3 |
|
nnacom |
⊢ ( ( 𝐴 ∈ ω ∧ 𝐵 ∈ ω ) → ( 𝐴 +o 𝐵 ) = ( 𝐵 +o 𝐴 ) ) |
4 |
1 2 3
|
syl2an |
⊢ ( ( 𝐴 ∈ N ∧ 𝐵 ∈ N ) → ( 𝐴 +o 𝐵 ) = ( 𝐵 +o 𝐴 ) ) |
5 |
|
addpiord |
⊢ ( ( 𝐴 ∈ N ∧ 𝐵 ∈ N ) → ( 𝐴 +N 𝐵 ) = ( 𝐴 +o 𝐵 ) ) |
6 |
|
addpiord |
⊢ ( ( 𝐵 ∈ N ∧ 𝐴 ∈ N ) → ( 𝐵 +N 𝐴 ) = ( 𝐵 +o 𝐴 ) ) |
7 |
6
|
ancoms |
⊢ ( ( 𝐴 ∈ N ∧ 𝐵 ∈ N ) → ( 𝐵 +N 𝐴 ) = ( 𝐵 +o 𝐴 ) ) |
8 |
4 5 7
|
3eqtr4d |
⊢ ( ( 𝐴 ∈ N ∧ 𝐵 ∈ N ) → ( 𝐴 +N 𝐵 ) = ( 𝐵 +N 𝐴 ) ) |
9 |
|
dmaddpi |
⊢ dom +N = ( N × N ) |
10 |
9
|
ndmovcom |
⊢ ( ¬ ( 𝐴 ∈ N ∧ 𝐵 ∈ N ) → ( 𝐴 +N 𝐵 ) = ( 𝐵 +N 𝐴 ) ) |
11 |
8 10
|
pm2.61i |
⊢ ( 𝐴 +N 𝐵 ) = ( 𝐵 +N 𝐴 ) |