| Step | Hyp | Ref
| Expression |
| 1 | | fveq2 6191 |
. . . . . . 7
 Vtx  Vtx    |
| 2 | 1 | adantr 481 |
. . . . . 6
 
 Vtx  Vtx    |
| 3 | | fveq2 6191 |
. . . . . . 7
 Vtx  Vtx    |
| 4 | 3 | adantl 482 |
. . . . . 6
 
 Vtx  Vtx    |
| 5 | 2, 4 | sseq12d 3634 |
. . . . 5
 
  Vtx 
Vtx  Vtx  Vtx     |
| 6 | | fveq2 6191 |
. . . . . . 7
 iEdg  iEdg    |
| 7 | 6 | adantr 481 |
. . . . . 6
 
 iEdg  iEdg    |
| 8 | | fveq2 6191 |
. . . . . . . 8
 iEdg  iEdg    |
| 9 | 8 | adantl 482 |
. . . . . . 7
 
 iEdg  iEdg    |
| 10 | 6 | dmeqd 5326 |
. . . . . . . 8
 iEdg  iEdg    |
| 11 | 10 | adantr 481 |
. . . . . . 7
 
 iEdg  iEdg    |
| 12 | 9, 11 | reseq12d 5397 |
. . . . . 6
 
  iEdg  iEdg    iEdg  iEdg     |
| 13 | 7, 12 | eqeq12d 2637 |
. . . . 5
 
  iEdg   iEdg  iEdg  
iEdg   iEdg  iEdg      |
| 14 | | fveq2 6191 |
. . . . . . 7
 Edg  Edg    |
| 15 | 1 | pweqd 4163 |
. . . . . . 7
  Vtx   Vtx    |
| 16 | 14, 15 | sseq12d 3634 |
. . . . . 6
  Edg   Vtx  Edg   Vtx     |
| 17 | 16 | adantr 481 |
. . . . 5
 
  Edg 
 Vtx 
Edg 
 Vtx     |
| 18 | 5, 13, 17 | 3anbi123d 1399 |
. . . 4
 
   Vtx  Vtx  iEdg   iEdg  iEdg  
Edg 
 Vtx  
 Vtx  Vtx  iEdg   iEdg  iEdg  
Edg 
 Vtx      |
| 19 | | df-subgr 26160 |
. . . 4
SubGraph      Vtx  Vtx  iEdg   iEdg  iEdg  
Edg 
 Vtx     |
| 20 | 18, 19 | brabga 4989 |
. . 3
 
  SubGraph
 Vtx  Vtx  iEdg   iEdg  iEdg  
Edg 
 Vtx      |
| 21 | 20 | ancoms 469 |
. 2
 
  SubGraph
 Vtx  Vtx  iEdg   iEdg  iEdg  
Edg 
 Vtx      |
| 22 | | issubgr.v |
. . . 4
Vtx   |
| 23 | | issubgr.a |
. . . 4
Vtx   |
| 24 | 22, 23 | sseq12i 3631 |
. . 3

Vtx 
Vtx    |
| 25 | | issubgr.i |
. . . 4
iEdg   |
| 26 | | issubgr.b |
. . . . 5
iEdg   |
| 27 | 25 | dmeqi 5325 |
. . . . 5
iEdg   |
| 28 | 26, 27 | reseq12i 5394 |
. . . 4
   iEdg  iEdg    |
| 29 | 25, 28 | eqeq12i 2636 |
. . 3
  
iEdg   iEdg  iEdg     |
| 30 | | issubgr.e |
. . . 4
Edg   |
| 31 | 22 | pweqi 4162 |
. . . 4
  Vtx   |
| 32 | 30, 31 | sseq12i 3631 |
. . 3
 
Edg 
 Vtx    |
| 33 | 24, 29, 32 | 3anbi123i 1251 |
. 2
 
     Vtx 
Vtx 
iEdg   iEdg  iEdg   Edg   Vtx     |
| 34 | 21, 33 | syl6bbr 278 |
1
 
  SubGraph
  
     |