Proof of Theorem wnbdi
| Step | Hyp | Ref
| Expression |
| 1 | | dfnb 87 |
. . 3
(a ≡ b)⊥ = ((a ∪ b) ∩
(a⊥ ∪ b⊥ )) |
| 2 | 1 | bi1 110 |
. 2
((a ≡ b)⊥ ≡ ((a ∪ b) ∩
(a⊥ ∪ b⊥ ))) = 1 |
| 3 | | wcomorr 394 |
. . . . 5
C (a, (a ∪ b)) =
1 |
| 4 | 3 | wcomcom 396 |
. . . 4
C ((a ∪ b), a) =
1 |
| 5 | 4 | wcomcom2 397 |
. . 3
C ((a ∪ b), a⊥ ) = 1 |
| 6 | | wcomorr 394 |
. . . . . 6
C (b, (b ∪ a)) =
1 |
| 7 | | ax-a2 30 |
. . . . . . 7
(b ∪ a) = (a ∪
b) |
| 8 | 7 | bi1 110 |
. . . . . 6
((b ∪ a) ≡ (a
∪ b)) = 1 |
| 9 | 6, 8 | wcbtr 393 |
. . . . 5
C (b, (a ∪ b)) =
1 |
| 10 | 9 | wcomcom 396 |
. . . 4
C ((a ∪ b), b) =
1 |
| 11 | 10 | wcomcom2 397 |
. . 3
C ((a ∪ b), b⊥ ) = 1 |
| 12 | 5, 11 | wfh1 405 |
. 2
(((a ∪ b) ∩ (a⊥ ∪ b⊥ )) ≡ (((a ∪ b) ∩
a⊥ ) ∪ ((a ∪ b) ∩
b⊥ ))) = 1 |
| 13 | 2, 12 | wr2 353 |
1
((a ≡ b)⊥ ≡ (((a ∪ b) ∩
a⊥ ) ∪ ((a ∪ b) ∩
b⊥ ))) = 1 |