Proof of Theorem istopgrp
| Step | Hyp | Ref
| Expression |
| 1 | | df-br 3339 |
. . . . 5
 TopGrp    TopGrp |
| 2 | | relopab 4104 |
. . . . . . 7
      Grp Top     Cn  inv   Cn     |
| 3 | | df-topgrp 14970 |
. . . . . . . 8
TopGrp       Grp Top     Cn  inv   Cn     |
| 4 | 3 | releqi 4072 |
. . . . . . 7
 TopGrp       Grp Top
    Cn
 inv 
 Cn      |
| 5 | 2, 4 | mpbir 207 |
. . . . . 6
TopGrp |
| 6 | 5 | brrelexi 4029 |
. . . . 5
 TopGrp   |
| 7 | 1, 6 | sylbir 218 |
. . . 4
    TopGrp   |
| 8 | 7 | adantl 424 |
. . 3
     TopGrp
  |
| 9 | | simpl 346 |
. . 3
     TopGrp
  |
| 10 | 8, 9 | jca 310 |
. 2
     TopGrp 
   |
| 11 | | elisset 2299 |
. . . . . 6
 Grp
  |
| 12 | 11 | adantr 425 |
. . . . 5
  Grp
Top
  |
| 13 | 12 | 3ad2ant1 897 |
. . . 4
   Grp
Top
    Cn
 inv   Cn     |
| 14 | 13 | adantl 424 |
. . 3
    Grp Top     Cn 
inv 
 Cn      |
| 15 | | simpl 346 |
. . 3
    Grp Top     Cn 
inv 
 Cn      |
| 16 | 14, 15 | jca 310 |
. 2
    Grp Top     Cn 
inv 
 Cn        |
| 17 | | eleq1 1957 |
. . . . . 6
  Grp Grp  |
| 18 | 17 | anbi1d 679 |
. . . . 5
   Grp Top  Grp
Top   |
| 19 | | eleq1 1957 |
. . . . 5
      Cn
     Cn     |
| 20 | | fveq2 4681 |
. . . . . 6
 inv  inv    |
| 21 | 20 | eleq1d 1963 |
. . . . 5
  inv   Cn  inv   Cn     |
| 22 | 18, 19, 21 | 3anbi123d 1168 |
. . . 4
    Grp Top     Cn  inv   Cn     Grp Top
    Cn
 inv 
 Cn      |
| 23 | | eleq1 1957 |
. . . . . 6
  Top Top  |
| 24 | 23 | anbi2d 678 |
. . . . 5
   Grp Top  Grp
Top   |
| 25 | | id 73 |
. . . . . . . 8
   |
| 26 | 25, 25 | opreq12d 4900 |
. . . . . . 7
         |
| 27 | 26, 25 | opreq12d 4900 |
. . . . . 6
     Cn      Cn    |
| 28 | 27 | eleq2d 1964 |
. . . . 5
      Cn
     Cn     |
| 29 | 25, 25 | opreq12d 4900 |
. . . . . 6
  Cn   Cn    |
| 30 | 29 | eleq2d 1964 |
. . . . 5
  inv 
 Cn  inv   Cn     |
| 31 | 24, 28, 30 | 3anbi123d 1168 |
. . . 4
    Grp Top     Cn  inv   Cn     Grp
Top
    Cn
 inv   Cn      |
| 32 | 22, 31 | opelopabg 3567 |
. . 3
 

  
       Grp
Top
    Cn  inv   Cn      Grp Top
    Cn  inv   Cn      |
| 33 | | df-topgrp 14970 |
. . . 4
TopGrp       Grp Top     Cn  inv   Cn     |
| 34 | 33 | eleq2i 1961 |
. . 3
    TopGrp   
  
   Grp Top     Cn  inv   Cn      |
| 35 | 32, 34 | syl5bb 591 |
. 2
 

  
 TopGrp   Grp
Top
    Cn
 inv   Cn      |
| 36 | 10, 16, 35 | pm5.21nd 744 |
1

   
TopGrp   Grp Top     Cn 
inv 
 Cn      |