| Step | Hyp | Ref
| Expression |
| 1 | | dfiso2.b |
. . . 4
     |
| 2 | | eqid 2622 |
. . . 4
Inv  Inv   |
| 3 | | dfiso2.c |
. . . 4
   |
| 4 | | dfiso2.x |
. . . 4
   |
| 5 | | dfiso2.y |
. . . 4
   |
| 6 | | dfiso2.i |
. . . 4
   |
| 7 | 1, 2, 3, 4, 5, 6 | isoval 16425 |
. . 3
       Inv      |
| 8 | 7 | eleq2d 2687 |
. 2
        Inv       |
| 9 | | eqid 2622 |
. . . . 5
Sect  Sect   |
| 10 | 1, 2, 3, 4, 5, 9 | invfval 16419 |
. . . 4
   Inv       Sect       Sect       |
| 11 | 10 | dmeqd 5326 |
. . 3
   Inv       Sect       Sect       |
| 12 | 11 | eleq2d 2687 |
. 2
    Inv   
   Sect       Sect        |
| 13 | | dfiso2.h |
. . . . . . . . 9
    |
| 14 | | eqid 2622 |
. . . . . . . . 9
comp  comp   |
| 15 | | dfiso2.1 |
. . . . . . . . 9
     |
| 16 | 1, 13, 14, 15, 9, 3, 4, 5 | sectfval 16411 |
. . . . . . . 8
   Sect                          comp            |
| 17 | 1, 13, 14, 15, 9, 3, 5, 4 | sectfval 16411 |
. . . . . . . . . 10
   Sect                          comp            |
| 18 | 17 | cnveqd 5298 |
. . . . . . . . 9
    Sect                           comp            |
| 19 | | cnvopab 5533 |
. . . . . . . . 9
                       comp                                comp           |
| 20 | 18, 19 | syl6eq 2672 |
. . . . . . . 8
    Sect                          comp            |
| 21 | 16, 20 | ineq12d 3815 |
. . . . . . 7
    Sect       Sect                            comp                                comp             |
| 22 | | inopab 5252 |
. . . . . . . 8
                       comp                                comp                                  comp                           comp            |
| 23 | | an4 865 |
. . . . . . . . . 10
                    comp                           comp                          
              comp               comp            |
| 24 | | an42 866 |
. . . . . . . . . . . 12
                      
     
                  |
| 25 | | anidm 676 |
. . . . . . . . . . . 12
                      
            |
| 26 | 24, 25 | bitri 264 |
. . . . . . . . . . 11
                      
            |
| 27 | 26 | anbi1i 731 |
. . . . . . . . . 10
                 
              comp               comp                          
  comp            
  comp            |
| 28 | 23, 27 | bitri 264 |
. . . . . . . . 9
                    comp                           comp                          
  comp            
  comp            |
| 29 | 28 | opabbii 4717 |
. . . . . . . 8
                       comp                           comp                                  comp               comp            |
| 30 | 22, 29 | eqtri 2644 |
. . . . . . 7
                       comp                                comp                                  comp               comp            |
| 31 | 21, 30 | syl6eq 2672 |
. . . . . 6
    Sect       Sect        
     
             comp            
  comp             |
| 32 | 31 | dmeqd 5326 |
. . . . 5
    Sect       Sect                            comp               comp             |
| 33 | | dmopab 5335 |
. . . . 5
                    
  comp            
  comp                              
  comp            
  comp            |
| 34 | 32, 33 | syl6eq 2672 |
. . . 4
    Sect       Sect             
             comp            
  comp             |
| 35 | 34 | eleq2d 2687 |
. . 3
     Sect       Sect    
                   
  comp            
  comp              |
| 36 | | dfiso2.f |
. . . 4
       |
| 37 | | eleq1 2689 |
. . . . . . . 8
     
       |
| 38 | 37 | anbi1d 741 |
. . . . . . 7
                         |
| 39 | | oveq2 6658 |
. . . . . . . . 9
        comp             comp        |
| 40 | 39 | eqeq1d 2624 |
. . . . . . . 8
      
  comp               comp           |
| 41 | | oveq1 6657 |
. . . . . . . . 9
        comp             comp        |
| 42 | 41 | eqeq1d 2624 |
. . . . . . . 8
      
  comp               comp           |
| 43 | 40, 42 | anbi12d 747 |
. . . . . . 7
          comp            
  comp                 comp               comp            |
| 44 | 38, 43 | anbi12d 747 |
. . . . . 6
                  
  comp            
  comp         
 
              
  comp            
  comp             |
| 45 | 44 | exbidv 1850 |
. . . . 5
                    
  comp            
  comp         
                  
  comp            
  comp             |
| 46 | 45 | elabg 3351 |
. . . 4
     
        
             comp            
  comp          
                  
  comp            
  comp             |
| 47 | 36, 46 | syl 17 |
. . 3
                     
  comp            
  comp          
                  
  comp            
  comp             |
| 48 | 36 | biantrurd 529 |
. . . . . . 7
                   |
| 49 | 48 | bicomd 213 |
. . . . . 6
           
       |
| 50 | | dfiso2.o |
. . . . . . . . . . 11
     comp     |
| 51 | 50 | a1i 11 |
. . . . . . . . . 10
   
  comp      |
| 52 | 51 | eqcomd 2628 |
. . . . . . . . 9
      comp     |
| 53 | 52 | oveqd 6667 |
. . . . . . . 8
     
  comp          |
| 54 | 53 | eqeq1d 2624 |
. . . . . . 7
         comp               |
| 55 | | dfiso2.p |
. . . . . . . . . . 11
     comp     |
| 56 | 55 | a1i 11 |
. . . . . . . . . 10
   
  comp      |
| 57 | 56 | eqcomd 2628 |
. . . . . . . . 9
      comp     |
| 58 | 57 | oveqd 6667 |
. . . . . . . 8
     
  comp          |
| 59 | 58 | eqeq1d 2624 |
. . . . . . 7
         comp               |
| 60 | 54, 59 | anbi12d 747 |
. . . . . 6
          comp               comp        
 

 
        |
| 61 | 49, 60 | anbi12d 747 |
. . . . 5
                  
  comp            
  comp         
                   |
| 62 | 61 | exbidv 1850 |
. . . 4
                       comp               comp                               |
| 63 | | df-rex 2918 |
. . . 4
                
           
        |
| 64 | 62, 63 | syl6bbr 278 |
. . 3
                       comp               comp          
                  |
| 65 | 35, 47, 64 | 3bitrd 294 |
. 2
     Sect       Sect    
          
        |
| 66 | 8, 12, 65 | 3bitrd 294 |
1
      
                  |