Proof of Theorem nbdi
| Step | Hyp | Ref
| Expression |
| 1 | | dfnb 87 |
. 2
(a ≡ b)⊥ = ((a ∪ b) ∩
(a⊥ ∪ b⊥ )) |
| 2 | | comorr 176 |
. . . . 5
a C (a ∪ b) |
| 3 | 2 | comcom 435 |
. . . 4
(a ∪ b) C a |
| 4 | 3 | comcom2 175 |
. . 3
(a ∪ b) C a⊥ |
| 5 | | comorr 176 |
. . . . . 6
b C (b ∪ a) |
| 6 | | ax-a2 30 |
. . . . . 6
(b ∪ a) = (a ∪
b) |
| 7 | 5, 6 | cbtr 174 |
. . . . 5
b C (a ∪ b) |
| 8 | 7 | comcom 435 |
. . . 4
(a ∪ b) C b |
| 9 | 8 | comcom2 175 |
. . 3
(a ∪ b) C b⊥ |
| 10 | 4, 9 | fh1 451 |
. 2
((a ∪ b) ∩ (a⊥ ∪ b⊥ )) = (((a ∪ b) ∩
a⊥ ) ∪ ((a ∪ b) ∩
b⊥ )) |
| 11 | 1, 10 | ax-r2 35 |
1
(a ≡ b)⊥ = (((a ∪ b) ∩
a⊥ ) ∪ ((a ∪ b) ∩
b⊥ )) |