Proof of Theorem ipdir
| Step | Hyp | Ref
| Expression |
| 1 | | fveq2 3724 |
. . . . . . 7
   CPreHil     
Base  Base   CPreHil         |
| 2 | | ipdir.1 |
. . . . . . 7
Base   |
| 3 | 1, 2 | syl5eq 1519 |
. . . . . 6
   CPreHil     
Base   CPreHil
  
     |
| 4 | 3 | eleq2d 1541 |
. . . . 5
   CPreHil     

Base   CPreHil
  
      |
| 5 | 3 | eleq2d 1541 |
. . . . 5
   CPreHil     

Base   CPreHil
  
      |
| 6 | 3 | eleq2d 1541 |
. . . . 5
   CPreHil     

Base   CPreHil
  
      |
| 7 | 4, 5, 6 | 3anbi123d 893 |
. . . 4
   CPreHil     
 
  Base   CPreHil       Base   CPreHil       Base   CPreHil           |
| 8 | | fveq2 3724 |
. . . . . . . . 9
   CPreHil     
         CPreHil 

      |
| 9 | | ipdir.2 |
. . . . . . . . 9
     |
| 10 | 8, 9 | syl5eq 1519 |
. . . . . . . 8
   CPreHil     
     CPreHil         |
| 11 | 10 | opreqd 3977 |
. . . . . . 7
   CPreHil     
           CPreHil
  
       |
| 12 | 11 | opreq1d 3975 |
. . . . . 6
   CPreHil     
                CPreHil              |
| 13 | | fveq2 3724 |
. . . . . . . 8
   CPreHil     
         CPreHil 

      |
| 14 | | ipdir.7 |
. . . . . . . 8
     |
| 15 | 13, 14 | syl5eq 1519 |
. . . . . . 7
   CPreHil     
     CPreHil 

      |
| 16 | 15 | opreqd 3977 |
. . . . . 6
   CPreHil     
        CPreHil                    CPreHil               CPreHil
  
       |
| 17 | 12, 16 | eqtrd 1507 |
. . . . 5
   CPreHil     
                CPreHil               CPreHil 

        |
| 18 | 15 | opreqd 3977 |
. . . . . 6
   CPreHil     
           CPreHil
  
       |
| 19 | 15 | opreqd 3977 |
. . . . . 6
   CPreHil     
           CPreHil
  
       |
| 20 | 18, 19 | opreq12d 3978 |
. . . . 5
   CPreHil     
                  CPreHil                CPreHil            |
| 21 | 17, 20 | eqeq12d 1489 |
. . . 4
   CPreHil     
                           CPreHil               CPreHil
  
             CPreHil                CPreHil             |
| 22 | 7, 21 | imbi12d 626 |
. . 3
   CPreHil     
                         Base   CPreHil       Base   CPreHil       Base   CPreHil                CPreHil               CPreHil
  
             CPreHil                CPreHil              |
| 23 | | eqid 1475 |
. . . 4
Base   CPreHil       Base   CPreHil 

     |
| 24 | | eqid 1475 |
. . . 4
     CPreHil
  
        CPreHil
  
    |
| 25 | | eqid 1475 |
. . . 4
     CPreHil
  
        CPreHil
  
    |
| 26 | | eqid 1475 |
. . . 4
     CPreHil
  
        CPreHil
  
    |
| 27 | | elimphu 8480 |
. . . 4
  CPreHil 

  
CPreHil |
| 28 | 23, 24, 25, 26, 27 | ipdiri 8489 |
. . 3
  Base   CPreHil       Base   CPreHil       Base   CPreHil                CPreHil               CPreHil
  
             CPreHil                CPreHil            |
| 29 | 22, 28 | dedth 2383 |
. 2

CPreHil  
                      |
| 30 | 29 | imp 350 |
1
  CPreHil 
                      |