| Step | Hyp | Ref
| Expression |
| 1 | | df-ushgr 25954 |
. . 3
USHGraph   Vtx   ![]. ].](_drbrack.gif)  iEdg   ![]. ].](_drbrack.gif)            |
| 2 | 1 | eleq2i 2693 |
. 2
 USHGraph   Vtx   ![]. ].](_drbrack.gif)  iEdg   ![]. ].](_drbrack.gif)             |
| 3 | | fveq2 6191 |
. . . . 5
 iEdg  iEdg    |
| 4 | | isuhgr.e |
. . . . 5
iEdg   |
| 5 | 3, 4 | syl6eqr 2674 |
. . . 4
 iEdg    |
| 6 | 3 | dmeqd 5326 |
. . . . 5
 iEdg  iEdg    |
| 7 | 4 | eqcomi 2631 |
. . . . . 6
iEdg   |
| 8 | 7 | dmeqi 5325 |
. . . . 5
iEdg   |
| 9 | 6, 8 | syl6eq 2672 |
. . . 4
 iEdg    |
| 10 | | fveq2 6191 |
. . . . . . 7
 Vtx  Vtx    |
| 11 | | isuhgr.v |
. . . . . . 7
Vtx   |
| 12 | 10, 11 | syl6eqr 2674 |
. . . . . 6
 Vtx    |
| 13 | 12 | pweqd 4163 |
. . . . 5
  Vtx     |
| 14 | 13 | difeq1d 3727 |
. . . 4
   Vtx            |
| 15 | 5, 9, 14 | f1eq123d 6131 |
. . 3
  iEdg    iEdg      Vtx    
            |
| 16 | | fvexd 6203 |
. . . . 5
 Vtx    |
| 17 | | fveq2 6191 |
. . . . 5
 Vtx  Vtx    |
| 18 | | fvexd 6203 |
. . . . . 6
 
Vtx   iEdg    |
| 19 | | fveq2 6191 |
. . . . . . 7
 iEdg  iEdg    |
| 20 | 19 | adantr 481 |
. . . . . 6
 
Vtx   iEdg  iEdg    |
| 21 | | simpr 477 |
. . . . . . 7
   Vtx   iEdg   iEdg    |
| 22 | 21 | dmeqd 5326 |
. . . . . . 7
   Vtx   iEdg  
iEdg    |
| 23 | | simpr 477 |
. . . . . . . . . 10
 
Vtx   Vtx    |
| 24 | 23 | pweqd 4163 |
. . . . . . . . 9
 
Vtx   
 Vtx    |
| 25 | 24 | difeq1d 3727 |
. . . . . . . 8
 
Vtx    
     Vtx       |
| 26 | 25 | adantr 481 |
. . . . . . 7
   Vtx   iEdg          Vtx       |
| 27 | 21, 22, 26 | f1eq123d 6131 |
. . . . . 6
   Vtx   iEdg            
iEdg    iEdg      Vtx        |
| 28 | 18, 20, 27 | sbcied2 3473 |
. . . . 5
 
Vtx     iEdg   ![]. ].](_drbrack.gif)          iEdg    iEdg      Vtx        |
| 29 | 16, 17, 28 | sbcied2 3473 |
. . . 4
   Vtx   ![]. ].](_drbrack.gif)  iEdg   ![]. ].](_drbrack.gif)         
iEdg    iEdg      Vtx        |
| 30 | 29 | cbvabv 2747 |
. . 3
  Vtx   ![]. ].](_drbrack.gif)  iEdg   ![]. ].](_drbrack.gif)           
iEdg    iEdg      Vtx 
     |
| 31 | 15, 30 | elab2g 3353 |
. 2
 
  Vtx   ![]. ].](_drbrack.gif)  iEdg   ![]. ].](_drbrack.gif)          
            |
| 32 | 2, 31 | syl5bb 272 |
1
 
USHGraph             |