| Step | Hyp | Ref
| Expression |
| 1 | | repsw 13522 |
. . . . 5
 
  repeatS
 Word   |
| 2 | 1 | 3adant3 1081 |
. . . 4
 
      repeatS  Word   |
| 3 | | repswlen 13523 |
. . . . . . . 8
 
     repeatS     |
| 4 | 3 | eqcomd 2628 |
. . . . . . 7
 

    repeatS     |
| 5 | 4 | oveq2d 6666 |
. . . . . 6
 
            repeatS      |
| 6 | 5 | eleq2d 2687 |
. . . . 5
 
             repeatS       |
| 7 | 6 | biimp3a 1432 |
. . . 4
 
            repeatS      |
| 8 | | pfxlen 41391 |
. . . 4
   repeatS
 Word        repeatS          repeatS
 prefix     |
| 9 | 2, 7, 8 | syl2anc 693 |
. . 3
 
          repeatS 
prefix     |
| 10 | | elfznn0 12433 |
. . . . . 6
       |
| 11 | 10 | anim2i 593 |
. . . . 5
 
         |
| 12 | 11 | 3adant2 1080 |
. . . 4
 
     
   |
| 13 | | repswlen 13523 |
. . . 4
 
     repeatS     |
| 14 | 12, 13 | syl 17 |
. . 3
 
         repeatS     |
| 15 | 9, 14 | eqtr4d 2659 |
. 2
 
          repeatS 
prefix       repeatS     |
| 16 | | simpl1 1064 |
. . . . 5
  
      ..^     repeatS
 prefix       |
| 17 | | simpl2 1065 |
. . . . 5
  
      ..^     repeatS
 prefix       |
| 18 | | elfzuz3 12339 |
. . . . . . . . 9
           |
| 19 | 18 | 3ad2ant3 1084 |
. . . . . . . 8
 
           |
| 20 | 9 | fveq2d 6195 |
. . . . . . . 8
 
             repeatS
 prefix          |
| 21 | 19, 20 | eleqtrrd 2704 |
. . . . . . 7
 
             repeatS
 prefix      |
| 22 | | fzoss2 12496 |
. . . . . . 7
         repeatS 
prefix   
 ..^     repeatS
 prefix     ..^   |
| 23 | 21, 22 | syl 17 |
. . . . . 6
 
      ..^     repeatS
 prefix     ..^   |
| 24 | 23 | sselda 3603 |
. . . . 5
  
      ..^     repeatS
 prefix      ..^   |
| 25 | | repswsymb 13521 |
. . . . 5
 
 ..^ 
  repeatS       |
| 26 | 16, 17, 24, 25 | syl3anc 1326 |
. . . 4
  
      ..^     repeatS
 prefix       repeatS       |
| 27 | 2 | adantr 481 |
. . . . 5
  
      ..^     repeatS
 prefix      repeatS  Word
  |
| 28 | 7 | adantr 481 |
. . . . 5
  
      ..^     repeatS
 prefix            repeatS
     |
| 29 | 9 | oveq2d 6666 |
. . . . . . 7
 
      ..^     repeatS
 prefix     ..^   |
| 30 | 29 | eleq2d 2687 |
. . . . . 6
 
       ..^     repeatS
 prefix   
 ..^    |
| 31 | 30 | biimpa 501 |
. . . . 5
  
      ..^     repeatS
 prefix      ..^   |
| 32 | | pfxfv 41399 |
. . . . 5
   repeatS
 Word        repeatS   
 ..^     repeatS 
prefix       repeatS
      |
| 33 | 27, 28, 31, 32 | syl3anc 1326 |
. . . 4
  
      ..^     repeatS
 prefix        repeatS  prefix       repeatS       |
| 34 | 10 | 3ad2ant3 1084 |
. . . . . 6
 
       |
| 35 | 34 | adantr 481 |
. . . . 5
  
      ..^     repeatS
 prefix       |
| 36 | | repswsymb 13521 |
. . . . 5
 
 ..^ 
  repeatS       |
| 37 | 16, 35, 31, 36 | syl3anc 1326 |
. . . 4
  
      ..^     repeatS
 prefix       repeatS       |
| 38 | 26, 33, 37 | 3eqtr4d 2666 |
. . 3
  
      ..^     repeatS
 prefix        repeatS  prefix       repeatS       |
| 39 | 38 | ralrimiva 2966 |
. 2
 
       ..^     repeatS  prefix        repeatS 
prefix       repeatS
      |
| 40 | | pfxcl 41386 |
. . . 4
  repeatS  Word   repeatS  prefix  Word   |
| 41 | 2, 40 | syl 17 |
. . 3
 
       repeatS
 prefix  Word   |
| 42 | | repsw 13522 |
. . . 4
 
  repeatS
 Word   |
| 43 | 12, 42 | syl 17 |
. . 3
 
      repeatS  Word   |
| 44 | | eqwrd 13346 |
. . 3
    repeatS  prefix  Word  repeatS
 Word     repeatS  prefix   repeatS 
      repeatS 
prefix       repeatS     ..^     repeatS
 prefix        repeatS  prefix       repeatS         |
| 45 | 41, 43, 44 | syl2anc 693 |
. 2
 
        repeatS  prefix   repeatS 
      repeatS 
prefix       repeatS     ..^     repeatS
 prefix        repeatS  prefix       repeatS         |
| 46 | 15, 39, 45 | mpbir2and 957 |
1
 
       repeatS
 prefix   repeatS    |