Proof of Theorem nbuhgr
| Step | Hyp | Ref
| Expression |
| 1 | | nbgrel.v |
. . . 4
Vtx   |
| 2 | | nbgrel.e |
. . . 4
Edg   |
| 3 | 1, 2 | nbgrval 26234 |
. . 3
  NeighbVtx       
      |
| 4 | 3 | a1d 25 |
. 2
   UHGraph   NeighbVtx       
       |
| 5 | | df-nel 2898 |
. . . . . 6

  |
| 6 | 1 | nbgrnvtx0 26237 |
. . . . . 6
  NeighbVtx    |
| 7 | 5, 6 | sylbir 225 |
. . . . 5
 
NeighbVtx    |
| 8 | 7 | adantr 481 |
. . . 4
   UHGraph   
NeighbVtx    |
| 9 | | simpl 473 |
. . . . . . . . . . . 12
  UHGraph
 UHGraph  |
| 10 | 9 | adantr 481 |
. . . . . . . . . . 11
   UHGraph      
UHGraph  |
| 11 | 2 | eleq2i 2693 |
. . . . . . . . . . . 12

Edg    |
| 12 | 11 | biimpi 206 |
. . . . . . . . . . 11
 Edg    |
| 13 | | edguhgr 26024 |
. . . . . . . . . . 11
  UHGraph
Edg  
 Vtx    |
| 14 | 10, 12, 13 | syl2an 494 |
. . . . . . . . . 10
    UHGraph


   
  Vtx    |
| 15 | | selpw 4165 |
. . . . . . . . . . . 12
  Vtx 
Vtx    |
| 16 | 1 | eqcomi 2631 |
. . . . . . . . . . . . 13
Vtx   |
| 17 | 16 | sseq2i 3630 |
. . . . . . . . . . . 12
 Vtx    |
| 18 | 15, 17 | bitri 264 |
. . . . . . . . . . 11
  Vtx 
  |
| 19 | | sstr 3611 |
. . . . . . . . . . . . . . 15
           |
| 20 | | vex 3203 |
. . . . . . . . . . . . . . . . 17
 |
| 21 | | prssg 4350 |
. . . . . . . . . . . . . . . . . 18
 
   
      |
| 22 | 21 | bicomd 213 |
. . . . . . . . . . . . . . . . 17
 
    

    |
| 23 | 20, 22 | mpan2 707 |
. . . . . . . . . . . . . . . 16
          |
| 24 | | simpl 473 |
. . . . . . . . . . . . . . . 16
 
   |
| 25 | 23, 24 | syl6bi 243 |
. . . . . . . . . . . . . . 15
    
   |
| 26 | 19, 25 | syl5com 31 |
. . . . . . . . . . . . . 14
      
   |
| 27 | 26 | ex 450 |
. . . . . . . . . . . . 13
   


    |
| 28 | 27 | com13 88 |
. . . . . . . . . . . 12
 
        |
| 29 | 28 | ad3antlr 767 |
. . . . . . . . . . 11
    UHGraph


   
     
    |
| 30 | 18, 29 | syl5bi 232 |
. . . . . . . . . 10
    UHGraph


   
   Vtx     
    |
| 31 | 14, 30 | mpd 15 |
. . . . . . . . 9
    UHGraph


   
    
   |
| 32 | 31 | rexlimdva 3031 |
. . . . . . . 8
   UHGraph           
   |
| 33 | 32 | con3rr3 151 |
. . . . . . 7
    UHGraph 

           |
| 34 | 33 | expdimp 453 |
. . . . . 6
   UHGraph          
    |
| 35 | 34 | ralrimiv 2965 |
. . . . 5
   UHGraph   
    
     |
| 36 | | rabeq0 3957 |
. . . . 5
      
   
     
 
   |
| 37 | 35, 36 | sylibr 224 |
. . . 4
   UHGraph   
    
   
  |
| 38 | 8, 37 | eqtr4d 2659 |
. . 3
   UHGraph   
NeighbVtx       
 
    |
| 39 | 38 | ex 450 |
. 2
   UHGraph

 NeighbVtx       
 
     |
| 40 | 4, 39 | pm2.61i 176 |
1
  UHGraph
  NeighbVtx       
      |