Proof of Theorem raaan
| Step | Hyp | Ref
| Expression |
| 1 | | pm5.1 501 |
. . 3
⊢ ((∀x ∈ A
∀y ∈ A (φ ∧
ψ) ∧ (∀x ∈ A φ ∧ ∀y ∈ A ψ)) → (∀x ∈ A
∀y ∈ A (φ ∧
ψ) ↔ (∀x ∈ A φ ∧ ∀y ∈ A ψ))) |
| 2 | | rzal 1773 |
. . 3
⊢ (A =
∅ → ∀x ∈ A ∀y
∈ A (φ ∧ ψ)) |
| 3 | | rzal 1773 |
. . . 4
⊢ (A =
∅ → ∀x ∈ A φ) |
| 4 | | rzal 1773 |
. . . 4
⊢ (A =
∅ → ∀y ∈ A ψ) |
| 5 | 3, 4 | jca 236 |
. . 3
⊢ (A =
∅ → (∀x ∈ A φ ∧
∀y ∈ A ψ)) |
| 6 | 1, 2, 5 | sylanc 361 |
. 2
⊢ (A =
∅ → (∀x ∈ A ∀y
∈ A (φ ∧ ψ) ↔ (∀x ∈ A φ ∧ ∀y ∈ A ψ))) |
| 7 | | r19.3rzv 1767 |
. . . . . 6
⊢ (¬ A = ∅ → (φ ↔ ∀y ∈ A φ)) |
| 8 | 7 | anbi1d 469 |
. . . . 5
⊢ (¬ A = ∅ → ((φ ∧ ∀y ∈ A ψ) ↔ (∀y ∈ A φ ∧ ∀y ∈ A ψ))) |
| 9 | | r19.26 1289 |
. . . . 5
⊢ (∀y ∈ A
(φ ∧ ψ) ↔ (∀y ∈ A φ ∧ ∀y ∈ A ψ)) |
| 10 | 8, 9 | syl6rbbr 417 |
. . . 4
⊢ (¬ A = ∅ → (∀y ∈ A
(φ ∧ ψ) ↔ (φ ∧ ∀y ∈ A ψ))) |
| 11 | 10 | biraldv 1219 |
. . 3
⊢ (¬ A = ∅ → (∀x ∈ A
∀y ∈ A (φ ∧
ψ) ↔ ∀x ∈ A
(φ ∧ ∀y ∈ A ψ))) |
| 12 | | r19.3rzv 1767 |
. . . . 5
⊢ (¬ A = ∅ → (∀y ∈ A ψ ↔ ∀x ∈ A
∀y ∈ A ψ)) |
| 13 | 12 | anbi2d 468 |
. . . 4
⊢ (¬ A = ∅ → ((∀x ∈ A φ ∧ ∀y ∈ A ψ) ↔ (∀x ∈ A φ ∧ ∀x ∈ A
∀y ∈ A ψ))) |
| 14 | | r19.26 1289 |
. . . 4
⊢ (∀x ∈ A
(φ ∧ ∀y ∈ A ψ) ↔ (∀x ∈ A φ ∧ ∀x ∈ A
∀y ∈ A ψ)) |
| 15 | 13, 14 | syl6rbbr 417 |
. . 3
⊢ (¬ A = ∅ → (∀x ∈ A
(φ ∧ ∀y ∈ A ψ) ↔ (∀x ∈ A φ ∧ ∀y ∈ A ψ))) |
| 16 | 11, 15 | bitrd 406 |
. 2
⊢ (¬ A = ∅ → (∀x ∈ A
∀y ∈ A (φ ∧
ψ) ↔ (∀x ∈ A φ ∧ ∀y ∈ A ψ))) |
| 17 | 6, 16 | pm2.61i 110 |
1
⊢ (∀x ∈ A
∀y ∈ A (φ ∧
ψ) ↔ (∀x ∈ A φ ∧ ∀y ∈ A ψ)) |