Proof of Theorem brdom4
| Step | Hyp | Ref
| Expression |
| 1 | | brdom4.1 |
. . . 4
 |
| 2 | | brdom4.2 |
. . . 4
 |
| 3 | 1, 2 | brdom3 4725 |
. . 3
                |
| 4 | | moan 1399 |
. . . . . . 7
            |
| 5 | 4 | 19.20i 968 |
. . . . . 6
                |
| 6 | | alral 1668 |
. . . . . 6
         
        |
| 7 | 5, 6 | syl 10 |
. . . . 5
               |
| 8 | 7 | anim1i 334 |
. . . 4
                    

     |
| 9 | 8 | 19.22i 1016 |
. . 3
         

             

     |
| 10 | 3, 9 | sylbi 199 |
. 2
    
      

     |
| 11 | | inss2 2202 |
. . . . . . . . . . . . . 14
       |
| 12 | | dmss 3267 |
. . . . . . . . . . . . . 14
      
  
   |
| 13 | 11, 12 | ax-mp 7 |
. . . . . . . . . . . . 13
  
  |
| 14 | | dmxpss 3422 |
. . . . . . . . . . . . 13
  |
| 15 | 13, 14 | sstri 2044 |
. . . . . . . . . . . 12
    |
| 16 | 15 | sseli 2036 |
. . . . . . . . . . 11

     |
| 17 | | rnss 3301 |
. . . . . . . . . . . . . . . 16
      
  
   |
| 18 | 11, 17 | ax-mp 7 |
. . . . . . . . . . . . . . 15
  
  |
| 19 | | rnxpss 3423 |
. . . . . . . . . . . . . . 15
  |
| 20 | 18, 19 | sstri 2044 |
. . . . . . . . . . . . . 14
    |
| 21 | 20 | sseli 2036 |
. . . . . . . . . . . . 13

     |
| 22 | | inss1 2201 |
. . . . . . . . . . . . . 14
     |
| 23 | 22 | ssbri 2625 |
. . . . . . . . . . . . 13
           |
| 24 | 21, 23 | anim12i 333 |
. . . . . . . . . . . 12
                  |
| 25 | 24 | immoi 1395 |
. . . . . . . . . . 11
                      |
| 26 | 16, 25 | imim12i 18 |
. . . . . . . . . 10
                             |
| 27 | 26 | r19.20i2 1679 |
. . . . . . . . 9
               
            |
| 28 | | relxp 3217 |
. . . . . . . . . 10

  |
| 29 | | relin2 3225 |
. . . . . . . . . 10
         |
| 30 | 28, 29 | ax-mp 7 |
. . . . . . . . 9
     |
| 31 | 27, 30 | jctil 292 |
. . . . . . . 8
                    
             |
| 32 | | dffun8 3482 |
. . . . . . . 8
          
                    |
| 33 | 31, 32 | sylibr 200 |
. . . . . . 7
              |
| 34 | | funfn 3483 |
. . . . . . 7
              |
| 35 | 33, 34 | sylib 198 |
. . . . . 6
           
     |
| 36 | | rninxp 3428 |
. . . . . . 7

         |
| 37 | 36 | biimpr 152 |
. . . . . 6
    
     |
| 38 | 35, 37 | anim12i 333 |
. . . . 5
                            |
| 39 | | df-fo 3159 |
. . . . 5
      
            
      |
| 40 | 38, 39 | sylibr 200 |
. . . 4
                           |
| 41 | | visset 1788 |
. . . . . . 7
 |
| 42 | 41 | inex1 2684 |
. . . . . 6
     |
| 43 | | dmexg 3289 |
. . . . . 6
    
     |
| 44 | 42, 43 | ax-mp 7 |
. . . . 5
    |
| 45 | 44 | fodom 4722 |
. . . 4
      
    
     |
| 46 | | ssdom2g 4344 |
. . . . . 6


  
      |
| 47 | 2, 15, 46 | mp2 43 |
. . . . 5
    |
| 48 | | domtr 4350 |
. . . . 5
 
         |
| 49 | 47, 48 | mpan2 693 |
. . . 4
      |
| 50 | 40, 45, 49 | 3syl 20 |
. . 3
                |
| 51 | 50 | 19.23aiv 1277 |
. 2
           

     |
| 52 | 10, 51 | impbi 157 |
1
                  |