Proof of Theorem subaddt
| Step | Hyp | Ref
| Expression |
| 1 | | opreq1 3006 |
. . . 4
⊢ (A =
if(A ∈ ℂ, A, 0) → (A
− B) = (if(A ∈ ℂ, A, 0) − B)) |
| 2 | 1 | cleq1d 1109 |
. . 3
⊢ (A =
if(A ∈ ℂ, A, 0) → ((A
− B) = C ↔ (if(A
∈ ℂ, A, 0) − B) = C)) |
| 3 | | cleq2 1110 |
. . 3
⊢ (A =
if(A ∈ ℂ, A, 0) → ((B
+ C) = A ↔ (B +
C) = if(A ∈ ℂ, A, 0))) |
| 4 | 2, 3 | bibi12d 477 |
. 2
⊢ (A =
if(A ∈ ℂ, A, 0) → (((A − B) =
C ↔ (B + C) =
A) ↔ ((if(A ∈ ℂ, A, 0) − B)
= C ↔ (B + C) =
if(A ∈ ℂ, A, 0)))) |
| 5 | | opreq2 3007 |
. . . 4
⊢ (B =
if(B ∈ ℂ, B, 0) → (if(A ∈ ℂ, A, 0) − B)
= (if(A ∈ ℂ, A, 0) − if(B ∈ ℂ, B, 0))) |
| 6 | 5 | cleq1d 1109 |
. . 3
⊢ (B =
if(B ∈ ℂ, B, 0) → ((if(A ∈ ℂ, A, 0) − B)
= C ↔ (if(A ∈ ℂ, A, 0) − if(B ∈ ℂ, B, 0)) = C)) |
| 7 | | opreq1 3006 |
. . . 4
⊢ (B =
if(B ∈ ℂ, B, 0) → (B
+ C) = (if(B ∈ ℂ, B, 0) + C)) |
| 8 | 7 | cleq1d 1109 |
. . 3
⊢ (B =
if(B ∈ ℂ, B, 0) → ((B
+ C) = if(A ∈ ℂ, A, 0) ↔ (if(B ∈ ℂ, B, 0) + C) =
if(A ∈ ℂ, A, 0))) |
| 9 | 6, 8 | bibi12d 477 |
. 2
⊢ (B =
if(B ∈ ℂ, B, 0) → (((if(A ∈ ℂ, A, 0) − B)
= C ↔ (B + C) =
if(A ∈ ℂ, A, 0)) ↔ ((if(A ∈ ℂ, A, 0) − if(B ∈ ℂ, B, 0)) = C
↔ (if(B ∈ ℂ, B, 0) + C) =
if(A ∈ ℂ, A, 0)))) |
| 10 | | cleq2 1110 |
. . 3
⊢ (C =
if(C ∈ ℂ, C, 0) → ((if(A ∈ ℂ, A, 0) − if(B ∈ ℂ, B, 0)) = C
↔ (if(A ∈ ℂ, A, 0) − if(B ∈ ℂ, B, 0)) = if(C
∈ ℂ, C, 0))) |
| 11 | | opreq2 3007 |
. . . 4
⊢ (C =
if(C ∈ ℂ, C, 0) → (if(B ∈ ℂ, B, 0) + C) =
(if(B ∈ ℂ, B, 0) + if(C
∈ ℂ, C, 0))) |
| 12 | 11 | cleq1d 1109 |
. . 3
⊢ (C =
if(C ∈ ℂ, C, 0) → ((if(B ∈ ℂ, B, 0) + C) =
if(A ∈ ℂ, A, 0) ↔ (if(B ∈ ℂ, B, 0) + if(C
∈ ℂ, C, 0)) = if(A ∈ ℂ, A, 0))) |
| 13 | 10, 12 | bibi12d 477 |
. 2
⊢ (C =
if(C ∈ ℂ, C, 0) → (((if(A ∈ ℂ, A, 0) − if(B ∈ ℂ, B, 0)) = C
↔ (if(B ∈ ℂ, B, 0) + C) =
if(A ∈ ℂ, A, 0)) ↔ ((if(A ∈ ℂ, A, 0) − if(B ∈ ℂ, B, 0)) = if(C
∈ ℂ, C, 0) ↔ (if(B ∈ ℂ, B, 0) + if(C
∈ ℂ, C, 0)) = if(A ∈ ℂ, A, 0)))) |
| 14 | | 0cn 4100 |
. . . 4
⊢ 0 ∈ ℂ |
| 15 | 14 | elimel 1793 |
. . 3
⊢ if(A
∈ ℂ, A, 0) ∈
ℂ |
| 16 | 14 | elimel 1793 |
. . 3
⊢ if(B
∈ ℂ, B, 0) ∈
ℂ |
| 17 | 14 | elimel 1793 |
. . 3
⊢ if(C
∈ ℂ, C, 0) ∈
ℂ |
| 18 | 15, 16, 17 | subadd 4143 |
. 2
⊢ ((if(A
∈ ℂ, A, 0) − if(B ∈ ℂ, B, 0)) = if(C
∈ ℂ, C, 0) ↔ (if(B ∈ ℂ, B, 0) + if(C
∈ ℂ, C, 0)) = if(A ∈ ℂ, A, 0)) |
| 19 | 4, 9, 13, 18 | dedth3h 1788 |
1
⊢ ((A
∈ ℂ ∧ B ∈ ℂ ∧
C ∈ ℂ) → ((A − B) =
C ↔ (B + C) =
A)) |