| Step | Hyp | Ref
 | Expression | 
| 1 |   | elin 3220 | 
. . . . 5
⊢ (y ∈ (B ∩ (◡S
“ {(H ‘D)})) ↔ (y
∈ B ∧ y ∈ (◡S
“ {(H ‘D)}))) | 
| 2 |   | eliniseg 5021 | 
. . . . . 6
⊢ (y ∈ (◡S
“ {(H ‘D)}) ↔ yS(H ‘D)) | 
| 3 | 2 | anbi2i 675 | 
. . . . 5
⊢ ((y ∈ B ∧ y ∈ (◡S
“ {(H ‘D)})) ↔ (y
∈ B ∧ yS(H
‘D))) | 
| 4 | 1, 3 | bitri 240 | 
. . . 4
⊢ (y ∈ (B ∩ (◡S
“ {(H ‘D)})) ↔ (y
∈ B ∧ yS(H
‘D))) | 
| 5 |   | isof1o 5489 | 
. . . . . . . . . . 11
⊢ (H Isom R,
S (A,
B) → H:A–1-1-onto→B) | 
| 6 |   | f1ofo 5294 | 
. . . . . . . . . . 11
⊢ (H:A–1-1-onto→B →
H:A–onto→B) | 
| 7 | 5, 6 | syl 15 | 
. . . . . . . . . 10
⊢ (H Isom R,
S (A,
B) → H:A–onto→B) | 
| 8 |   | forn 5273 | 
. . . . . . . . . 10
⊢ (H:A–onto→B
→ ran H = B) | 
| 9 | 7, 8 | syl 15 | 
. . . . . . . . 9
⊢ (H Isom R,
S (A,
B) → ran H = B) | 
| 10 | 9 | eleq2d 2420 | 
. . . . . . . 8
⊢ (H Isom R,
S (A,
B) → (y ∈ ran H ↔ y ∈ B)) | 
| 11 |   | f1ofn 5289 | 
. . . . . . . . . 10
⊢ (H:A–1-1-onto→B →
H Fn A) | 
| 12 | 5, 11 | syl 15 | 
. . . . . . . . 9
⊢ (H Isom R,
S (A,
B) → H Fn A) | 
| 13 |   | fvelrnb 5366 | 
. . . . . . . . 9
⊢ (H Fn A →
(y ∈ ran
H ↔ ∃x ∈ A (H ‘x) =
y)) | 
| 14 | 12, 13 | syl 15 | 
. . . . . . . 8
⊢ (H Isom R,
S (A,
B) → (y ∈ ran H ↔ ∃x ∈ A (H ‘x) =
y)) | 
| 15 | 10, 14 | bitr3d 246 | 
. . . . . . 7
⊢ (H Isom R,
S (A,
B) → (y ∈ B ↔ ∃x ∈ A (H ‘x) =
y)) | 
| 16 | 15 | anbi1d 685 | 
. . . . . 6
⊢ (H Isom R,
S (A,
B) → ((y ∈ B ∧ yS(H ‘D))
↔ (∃x ∈ A (H
‘x) = y ∧ yS(H ‘D)))) | 
| 17 | 16 | adantr 451 | 
. . . . 5
⊢ ((H Isom R,
S (A,
B) ∧
D ∈
A) → ((y ∈ B ∧ yS(H ‘D))
↔ (∃x ∈ A (H
‘x) = y ∧ yS(H ‘D)))) | 
| 18 |   | elin 3220 | 
. . . . . . . . . . 11
⊢ (x ∈ (A ∩ (◡R
“ {D})) ↔ (x ∈ A ∧ x ∈ (◡R
“ {D}))) | 
| 19 |   | eliniseg 5021 | 
. . . . . . . . . . . 12
⊢ (x ∈ (◡R
“ {D}) ↔ xRD) | 
| 20 | 19 | anbi2i 675 | 
. . . . . . . . . . 11
⊢ ((x ∈ A ∧ x ∈ (◡R
“ {D})) ↔ (x ∈ A ∧ xRD)) | 
| 21 | 18, 20 | bitri 240 | 
. . . . . . . . . 10
⊢ (x ∈ (A ∩ (◡R
“ {D})) ↔ (x ∈ A ∧ xRD)) | 
| 22 | 21 | anbi1i 676 | 
. . . . . . . . 9
⊢ ((x ∈ (A ∩ (◡R
“ {D})) ∧ xHy) ↔
((x ∈
A ∧
xRD) ∧ xHy)) | 
| 23 |   | anass 630 | 
. . . . . . . . 9
⊢ (((x ∈ A ∧ xRD) ∧ xHy) ↔ (x
∈ A ∧ (xRD ∧ xHy))) | 
| 24 | 22, 23 | bitri 240 | 
. . . . . . . 8
⊢ ((x ∈ (A ∩ (◡R
“ {D})) ∧ xHy) ↔
(x ∈
A ∧
(xRD ∧ xHy))) | 
| 25 |   | fnbrfvb 5359 | 
. . . . . . . . . . . . . . . . 17
⊢ ((H Fn A ∧ x ∈ A) →
((H ‘x) = y ↔
xHy)) | 
| 26 | 12, 25 | sylan 457 | 
. . . . . . . . . . . . . . . 16
⊢ ((H Isom R,
S (A,
B) ∧
x ∈
A) → ((H ‘x) =
y ↔ xHy)) | 
| 27 | 26 | adantrr 697 | 
. . . . . . . . . . . . . . 15
⊢ ((H Isom R,
S (A,
B) ∧
(x ∈
A ∧
D ∈
A)) → ((H ‘x) =
y ↔ xHy)) | 
| 28 | 27 | bicomd 192 | 
. . . . . . . . . . . . . 14
⊢ ((H Isom R,
S (A,
B) ∧
(x ∈
A ∧
D ∈
A)) → (xHy ↔ (H
‘x) = y)) | 
| 29 |   | isorel 5490 | 
. . . . . . . . . . . . . 14
⊢ ((H Isom R,
S (A,
B) ∧
(x ∈
A ∧
D ∈
A)) → (xRD ↔ (H
‘x)S(H
‘D))) | 
| 30 | 28, 29 | anbi12d 691 | 
. . . . . . . . . . . . 13
⊢ ((H Isom R,
S (A,
B) ∧
(x ∈
A ∧
D ∈
A)) → ((xHy ∧ xRD) ↔ ((H
‘x) = y ∧ (H ‘x)S(H ‘D)))) | 
| 31 |   | ancom 437 | 
. . . . . . . . . . . . 13
⊢ ((xHy ∧ xRD) ↔ (xRD ∧ xHy)) | 
| 32 |   | breq1 4643 | 
. . . . . . . . . . . . . 14
⊢ ((H ‘x) =
y → ((H ‘x)S(H ‘D)
↔ yS(H
‘D))) | 
| 33 | 32 | pm5.32i 618 | 
. . . . . . . . . . . . 13
⊢ (((H ‘x) =
y ∧
(H ‘x)S(H ‘D))
↔ ((H ‘x) = y ∧ yS(H
‘D))) | 
| 34 | 30, 31, 33 | 3bitr3g 278 | 
. . . . . . . . . . . 12
⊢ ((H Isom R,
S (A,
B) ∧
(x ∈
A ∧
D ∈
A)) → ((xRD ∧ xHy) ↔ ((H
‘x) = y ∧ yS(H ‘D)))) | 
| 35 | 34 | exp32 588 | 
. . . . . . . . . . 11
⊢ (H Isom R,
S (A,
B) → (x ∈ A → (D
∈ A
→ ((xRD ∧ xHy) ↔
((H ‘x) = y ∧ yS(H
‘D)))))) | 
| 36 | 35 | com23 72 | 
. . . . . . . . . 10
⊢ (H Isom R,
S (A,
B) → (D ∈ A → (x
∈ A
→ ((xRD ∧ xHy) ↔
((H ‘x) = y ∧ yS(H
‘D)))))) | 
| 37 | 36 | imp 418 | 
. . . . . . . . 9
⊢ ((H Isom R,
S (A,
B) ∧
D ∈
A) → (x ∈ A → ((xRD ∧ xHy) ↔ ((H
‘x) = y ∧ yS(H ‘D))))) | 
| 38 | 37 | pm5.32d 620 | 
. . . . . . . 8
⊢ ((H Isom R,
S (A,
B) ∧
D ∈
A) → ((x ∈ A ∧ (xRD ∧ xHy)) ↔ (x
∈ A ∧ ((H
‘x) = y ∧ yS(H ‘D))))) | 
| 39 | 24, 38 | syl5bb 248 | 
. . . . . . 7
⊢ ((H Isom R,
S (A,
B) ∧
D ∈
A) → ((x ∈ (A ∩ (◡R
“ {D})) ∧ xHy) ↔
(x ∈
A ∧
((H ‘x) = y ∧ yS(H
‘D))))) | 
| 40 | 39 | rexbidv2 2638 | 
. . . . . 6
⊢ ((H Isom R,
S (A,
B) ∧
D ∈
A) → (∃x ∈ (A ∩
(◡R
“ {D}))xHy ↔ ∃x ∈ A ((H ‘x) =
y ∧
yS(H
‘D)))) | 
| 41 |   | r19.41v 2765 | 
. . . . . 6
⊢ (∃x ∈ A ((H ‘x) =
y ∧
yS(H
‘D)) ↔ (∃x ∈ A (H ‘x) =
y ∧
yS(H
‘D))) | 
| 42 | 40, 41 | syl6bb 252 | 
. . . . 5
⊢ ((H Isom R,
S (A,
B) ∧
D ∈
A) → (∃x ∈ (A ∩
(◡R
“ {D}))xHy ↔ (∃x ∈ A (H ‘x) =
y ∧
yS(H
‘D)))) | 
| 43 | 17, 42 | bitr4d 247 | 
. . . 4
⊢ ((H Isom R,
S (A,
B) ∧
D ∈
A) → ((y ∈ B ∧ yS(H ‘D))
↔ ∃x ∈ (A ∩ (◡R
“ {D}))xHy)) | 
| 44 | 4, 43 | syl5bb 248 | 
. . 3
⊢ ((H Isom R,
S (A,
B) ∧
D ∈
A) → (y ∈ (B ∩ (◡S
“ {(H ‘D)})) ↔ ∃x ∈ (A ∩
(◡R
“ {D}))xHy)) | 
| 45 | 44 | eqabdv 2469 | 
. 2
⊢ ((H Isom R,
S (A,
B) ∧
D ∈
A) → (B ∩ (◡S
“ {(H ‘D)})) = {y ∣ ∃x ∈ (A ∩ (◡R
“ {D}))xHy}) | 
| 46 |   | df-ima 4728 | 
. 2
⊢ (H “ (A
∩ (◡R “ {D})))
= {y ∣
∃x ∈ (A ∩
(◡R
“ {D}))xHy} | 
| 47 | 45, 46 | syl6reqr 2404 | 
1
⊢ ((H Isom R,
S (A,
B) ∧
D ∈
A) → (H “ (A
∩ (◡R “ {D})))
= (B ∩ (◡S
“ {(H ‘D)}))) |