| Step | Hyp | Ref
| Expression |
| 1 | | elopab 4983 |
. . . . 5
         
               |
| 2 | | f0bi 6088 |
. . . . . . . . . 10
       |
| 3 | | opeq2 4403 |
. . . . . . . . . . . 12

        |
| 4 | | vex 3203 |
. . . . . . . . . . . . 13
 |
| 5 | | usgr0eop 26138 |
. . . . . . . . . . . . 13
   
USGraph  |
| 6 | 4, 5 | ax-mp 5 |
. . . . . . . . . . . 12
  
USGraph |
| 7 | 3, 6 | syl6eqel 2709 |
. . . . . . . . . . 11

   USGraph  |
| 8 | | vex 3203 |
. . . . . . . . . . . . 13
 |
| 9 | | opiedgfv 25887 |
. . . . . . . . . . . . 13
 
 iEdg       |
| 10 | 4, 8, 9 | mp2an 708 |
. . . . . . . . . . . 12
iEdg      |
| 11 | | id 22 |
. . . . . . . . . . . 12

  |
| 12 | 10, 11 | syl5eq 2668 |
. . . . . . . . . . 11

iEdg       |
| 13 | 7, 12 | jca 554 |
. . . . . . . . . 10

    USGraph iEdg        |
| 14 | 2, 13 | sylbi 207 |
. . . . . . . . 9
    
    USGraph iEdg        |
| 15 | 14 | adantl 482 |
. . . . . . . 8
              USGraph iEdg        |
| 16 | | eleq1 2689 |
. . . . . . . . . 10
     USGraph    USGraph   |
| 17 | | fveq2 6191 |
. . . . . . . . . . 11
    iEdg  iEdg       |
| 18 | 17 | eqeq1d 2624 |
. . . . . . . . . 10
     iEdg  iEdg        |
| 19 | 16, 18 | anbi12d 747 |
. . . . . . . . 9
      USGraph iEdg  
    USGraph iEdg         |
| 20 | 19 | adantr 481 |
. . . . . . . 8
            USGraph iEdg       USGraph iEdg         |
| 21 | 15, 20 | mpbird 247 |
. . . . . . 7
          
USGraph iEdg     |
| 22 | | fveq2 6191 |
. . . . . . . . 9
 iEdg  iEdg    |
| 23 | 22 | eqeq1d 2624 |
. . . . . . . 8
  iEdg  iEdg     |
| 24 | 23 | elrab 3363 |
. . . . . . 7
  USGraph iEdg  
 USGraph iEdg     |
| 25 | 21, 24 | sylibr 224 |
. . . . . 6
           USGraph iEdg     |
| 26 | 25 | exlimivv 1860 |
. . . . 5
               USGraph iEdg     |
| 27 | 1, 26 | sylbi 207 |
. . . 4
           USGraph iEdg     |
| 28 | 27 | ssriv 3607 |
. . 3
          USGraph
iEdg    |
| 29 | | eqid 2622 |
. . . 4
                   |
| 30 | 29 | griedg0prc 26156 |
. . 3
          |
| 31 | | prcssprc 4806 |
. . 3
     
    
 USGraph iEdg              USGraph iEdg     |
| 32 | 28, 30, 31 | mp2an 708 |
. 2
 USGraph
iEdg    |
| 33 | | df-3an 1039 |
. . . . . . . 8
  USGraph
NN0*  Vtx    VtxDeg     
 
USGraph NN0*
 Vtx    VtxDeg        |
| 34 | 33 | bicomi 214 |
. . . . . . 7
   USGraph NN0*  Vtx    VtxDeg     
 USGraph NN0*  Vtx    VtxDeg        |
| 35 | 34 | a1i 11 |
. . . . . 6
 USGraph    USGraph
NN0*  Vtx    VtxDeg     
 USGraph NN0*  Vtx    VtxDeg         |
| 36 | | 0xnn0 11369 |
. . . . . . 7
NN0* |
| 37 | | ibar 525 |
. . . . . . 7
  USGraph
NN0*
 
Vtx    VtxDeg       USGraph NN0*  Vtx    VtxDeg         |
| 38 | 36, 37 | mpan2 707 |
. . . . . 6
 USGraph   Vtx    VtxDeg    
 
USGraph NN0*
 Vtx    VtxDeg         |
| 39 | | eqid 2622 |
. . . . . . . 8
Vtx  Vtx   |
| 40 | | eqid 2622 |
. . . . . . . 8
VtxDeg  VtxDeg   |
| 41 | 39, 40 | isrusgr0 26462 |
. . . . . . 7
  USGraph
NN0*
 RegUSGraph  USGraph NN0*  Vtx    VtxDeg         |
| 42 | 36, 41 | mpan2 707 |
. . . . . 6
 USGraph  RegUSGraph  USGraph
NN0*  Vtx    VtxDeg         |
| 43 | 35, 38, 42 | 3bitr4d 300 |
. . . . 5
 USGraph   Vtx    VtxDeg    
RegUSGraph    |
| 44 | 43 | rabbiia 3185 |
. . . 4
 USGraph
 Vtx    VtxDeg       USGraph RegUSGraph   |
| 45 | | usgr0edg0rusgr 26471 |
. . . . . 6
 USGraph  RegUSGraph Edg     |
| 46 | | usgruhgr 26078 |
. . . . . . 7
 USGraph UHGraph  |
| 47 | | uhgriedg0edg0 26022 |
. . . . . . 7
 UHGraph  Edg  iEdg     |
| 48 | 46, 47 | syl 17 |
. . . . . 6
 USGraph  Edg  iEdg     |
| 49 | 45, 48 | bitrd 268 |
. . . . 5
 USGraph  RegUSGraph iEdg     |
| 50 | 49 | rabbiia 3185 |
. . . 4
 USGraph
RegUSGraph   USGraph iEdg    |
| 51 | 44, 50 | eqtri 2644 |
. . 3
 USGraph
 Vtx    VtxDeg       USGraph iEdg    |
| 52 | | neleq1 2902 |
. . 3
  USGraph

Vtx    VtxDeg       USGraph iEdg     USGraph 
Vtx    VtxDeg     
 USGraph iEdg      |
| 53 | 51, 52 | ax-mp 5 |
. 2
  USGraph

Vtx    VtxDeg     
 USGraph iEdg     |
| 54 | 32, 53 | mpbir 221 |
1
 USGraph
 Vtx    VtxDeg       |