Proof of Theorem rankelop
| Step | Hyp | Ref
| Expression |
| 1 | | rankelun.1 |
. . . . 5
⊢ A ∈
V |
| 2 | | rankelun.2 |
. . . . 5
⊢ B ∈
V |
| 3 | | rankelun.3 |
. . . . 5
⊢ C ∈
V |
| 4 | | rankelun.4 |
. . . . 5
⊢ D ∈
V |
| 5 | 1, 2, 3, 4 | rankelpr 4718 |
. . . 4
⊢ (((rank ‘A) ∈ (rank
‘C) ⋀ (rank ‘B) ∈ (rank
‘D)) → (rank ‘{A, B}) ∈ (rank ‘{C, D})) |
| 6 | | rankon 4681 |
. . . . . 6
⊢ (rank ‘{C, D}) ∈ On |
| 7 | 6 | onord 3101 |
. . . . 5
⊢ Ord (rank ‘{C, D}) |
| 8 | | ordsucelsuc 3079 |
. . . . 5
⊢ (Ord (rank
‘{C, D}) → ((rank ‘{A, B}) ∈ (rank ‘{C, D}) ↔
suc (rank ‘{A, B}) ∈ suc (rank
‘{C, D}))) |
| 9 | 7, 8 | ax-mp 7 |
. . . 4
⊢ ((rank ‘{A, B}) ∈ (rank ‘{C, D}) ↔
suc (rank ‘{A, B}) ∈ suc (rank
‘{C, D})) |
| 10 | 5, 9 | sylib 198 |
. . 3
⊢ (((rank ‘A) ∈ (rank
‘C) ⋀ (rank ‘B) ∈ (rank
‘D)) → suc (rank
‘{A, B}) ∈ suc (rank
‘{C, D})) |
| 11 | 3, 4 | rankpr 4702 |
. . . . 5
⊢ (rank ‘{C, D}) = suc
((rank ‘C) ∪ (rank
‘D)) |
| 12 | | suceq 3040 |
. . . . 5
⊢ ((rank ‘{C, D}) = suc
((rank ‘C) ∪ (rank
‘D)) → suc (rank
‘{C, D}) = suc suc ((rank ‘C) ∪ (rank ‘D))) |
| 13 | 11, 12 | ax-mp 7 |
. . . 4
⊢ suc (rank ‘{C, D}) = suc suc
((rank ‘C) ∪ (rank
‘D)) |
| 14 | 3, 4 | rankop 4703 |
. . . 4
⊢ (rank ‘〈C, D〉) = suc suc
((rank ‘C) ∪ (rank
‘D)) |
| 15 | 13, 14 | eqtr4 1501 |
. . 3
⊢ suc (rank ‘{C, D}) = (rank
‘〈C, D〉) |
| 16 | 10, 15 | syl6eleq 1561 |
. 2
⊢ (((rank ‘A) ∈ (rank
‘C) ⋀ (rank ‘B) ∈ (rank
‘D)) → suc (rank
‘{A, B}) ∈ (rank
‘〈C, D〉)) |
| 17 | 1, 2 | rankop 4703 |
. . 3
⊢ (rank ‘〈A, B〉) = suc suc
((rank ‘A) ∪ (rank
‘B)) |
| 18 | 1, 2 | rankpr 4702 |
. . . 4
⊢ (rank ‘{A, B}) = suc
((rank ‘A) ∪ (rank
‘B)) |
| 19 | | suceq 3040 |
. . . 4
⊢ ((rank ‘{A, B}) = suc
((rank ‘A) ∪ (rank
‘B)) → suc (rank
‘{A, B}) = suc suc ((rank ‘A) ∪ (rank ‘B))) |
| 20 | 18, 19 | ax-mp 7 |
. . 3
⊢ suc (rank ‘{A, B}) = suc suc
((rank ‘A) ∪ (rank
‘B)) |
| 21 | 17, 20 | eqtr4 1501 |
. 2
⊢ (rank ‘〈A, B〉) = suc (rank
‘{A, B}) |
| 22 | 16, 21 | syl5eqel 1555 |
1
⊢ (((rank ‘A) ∈ (rank
‘C) ⋀ (rank ‘B) ∈ (rank
‘D)) → (rank ‘〈A, B〉) ∈ (rank ‘〈C, D〉)) |