| Step | Hyp | Ref
| Expression |
| 1 | | dprdsplit.1 |
. . 3
  DProd
  |
| 2 | | dprdsplit.2 |
. . . 4
     SubGrp    |
| 3 | | fdm 6051 |
. . . 4
     SubGrp    |
| 4 | 2, 3 | syl 17 |
. . 3
   |
| 5 | | ssun1 3776 |
. . . . . . . 8

  |
| 6 | | dprdsplit.u |
. . . . . . . 8
     |
| 7 | 5, 6 | syl5sseqr 3654 |
. . . . . . 7

  |
| 8 | 1, 4, 7 | dprdres 18427 |
. . . . . 6
   DProd    DProd   
 DProd     |
| 9 | 8 | simpld 475 |
. . . . 5
  DProd
    |
| 10 | | dprdsubg 18423 |
. . . . 5
  DProd    DProd    SubGrp    |
| 11 | 9, 10 | syl 17 |
. . . 4
  DProd    SubGrp    |
| 12 | | ssun2 3777 |
. . . . . . . 8

  |
| 13 | 12, 6 | syl5sseqr 3654 |
. . . . . . 7

  |
| 14 | 1, 4, 13 | dprdres 18427 |
. . . . . 6
   DProd    DProd   
 DProd     |
| 15 | 14 | simpld 475 |
. . . . 5
  DProd
    |
| 16 | | dprdsubg 18423 |
. . . . 5
  DProd    DProd    SubGrp    |
| 17 | 15, 16 | syl 17 |
. . . 4
  DProd    SubGrp    |
| 18 | | dprdsplit.i |
. . . . . . 7
     |
| 19 | | eqid 2622 |
. . . . . . 7
Cntz  Cntz   |
| 20 | | eqid 2622 |
. . . . . . 7
         |
| 21 | 2, 18, 6, 19, 20 | dmdprdsplit 18446 |
. . . . . 6
   DProd
   DProd    DProd     DProd   
 Cntz     DProd       DProd
    DProd               |
| 22 | 1, 21 | mpbid 222 |
. . . . 5
    DProd 
  DProd
   
DProd     Cntz     DProd       DProd     DProd              |
| 23 | 22 | simp2d 1074 |
. . . 4
  DProd     Cntz     DProd       |
| 24 | | dprdsplit.s |
. . . . 5
     |
| 25 | 24, 19 | lsmsubg 18069 |
. . . 4
   DProd    SubGrp   DProd    SubGrp   DProd     Cntz     DProd     
  DProd   
 DProd 
   SubGrp    |
| 26 | 11, 17, 23, 25 | syl3anc 1326 |
. . 3
   DProd     DProd     SubGrp    |
| 27 | 6 | eleq2d 2687 |
. . . . . 6
       |
| 28 | | elun 3753 |
. . . . . 6
  

   |
| 29 | 27, 28 | syl6bb 276 |
. . . . 5
  
    |
| 30 | 29 | biimpa 501 |
. . . 4
 
 
   |
| 31 | | fvres 6207 |
. . . . . . . 8
             |
| 32 | 31 | adantl 482 |
. . . . . . 7
 
             |
| 33 | 9 | adantr 481 |
. . . . . . . 8
 
  DProd     |
| 34 | 2, 7 | fssresd 6071 |
. . . . . . . . . 10
       SubGrp    |
| 35 | | fdm 6051 |
. . . . . . . . . 10
 
     SubGrp      |
| 36 | 34, 35 | syl 17 |
. . . . . . . . 9
     |
| 37 | 36 | adantr 481 |
. . . . . . . 8
 
 
   |
| 38 | | simpr 477 |
. . . . . . . 8
 
   |
| 39 | 33, 37, 38 | dprdub 18424 |
. . . . . . 7
 
       
DProd      |
| 40 | 32, 39 | eqsstr3d 3640 |
. . . . . 6
 
      DProd      |
| 41 | 24 | lsmub1 18071 |
. . . . . . . 8
   DProd    SubGrp   DProd    SubGrp  
 DProd 
 
  DProd   
 DProd 
     |
| 42 | 11, 17, 41 | syl2anc 693 |
. . . . . . 7
  DProd      DProd     DProd       |
| 43 | 42 | adantr 481 |
. . . . . 6
 
  DProd   
  DProd   
 DProd 
     |
| 44 | 40, 43 | sstrd 3613 |
. . . . 5
 
       DProd     DProd       |
| 45 | | fvres 6207 |
. . . . . . . 8
             |
| 46 | 45 | adantl 482 |
. . . . . . 7
 
             |
| 47 | 15 | adantr 481 |
. . . . . . . 8
 
  DProd     |
| 48 | 2, 13 | fssresd 6071 |
. . . . . . . . . 10
       SubGrp    |
| 49 | | fdm 6051 |
. . . . . . . . . 10
 
     SubGrp      |
| 50 | 48, 49 | syl 17 |
. . . . . . . . 9
     |
| 51 | 50 | adantr 481 |
. . . . . . . 8
 
 
   |
| 52 | | simpr 477 |
. . . . . . . 8
 
   |
| 53 | 47, 51, 52 | dprdub 18424 |
. . . . . . 7
 
       
DProd      |
| 54 | 46, 53 | eqsstr3d 3640 |
. . . . . 6
 
      DProd      |
| 55 | 24 | lsmub2 18072 |
. . . . . . . 8
   DProd    SubGrp   DProd    SubGrp  
 DProd 
 
  DProd   
 DProd 
     |
| 56 | 11, 17, 55 | syl2anc 693 |
. . . . . . 7
  DProd      DProd     DProd       |
| 57 | 56 | adantr 481 |
. . . . . 6
 
  DProd   
  DProd   
 DProd 
     |
| 58 | 54, 57 | sstrd 3613 |
. . . . 5
 
       DProd     DProd       |
| 59 | 44, 58 | jaodan 826 |
. . . 4
 

     
  DProd   
 DProd 
     |
| 60 | 30, 59 | syldan 487 |
. . 3
 
       DProd     DProd       |
| 61 | 1, 4, 26, 60 | dprdlub 18425 |
. 2
  DProd    DProd   
 DProd 
     |
| 62 | 8 | simprd 479 |
. . 3
  DProd    
DProd    |
| 63 | 14 | simprd 479 |
. . 3
  DProd    
DProd    |
| 64 | | dprdsubg 18423 |
. . . . 5
  DProd
 DProd  SubGrp    |
| 65 | 1, 64 | syl 17 |
. . . 4
  DProd  SubGrp    |
| 66 | 24 | lsmlub 18078 |
. . . 4
   DProd    SubGrp   DProd    SubGrp   DProd  SubGrp      DProd     DProd 
 DProd 
 
 DProd  
  DProd   
 DProd 
    DProd     |
| 67 | 11, 17, 65, 66 | syl3anc 1326 |
. . 3
    DProd   
 DProd   DProd   
 DProd  
  DProd   
 DProd 
    DProd     |
| 68 | 62, 63, 67 | mpbi2and 956 |
. 2
   DProd     DProd    
 DProd    |
| 69 | 61, 68 | eqssd 3620 |
1
  DProd    DProd   
 DProd 
     |