Proof of Theorem ccatopth
| Step | Hyp | Ref
| Expression |
| 1 | | oveq1 5963 |
. . . . 5
  ++   ++    ++  prefix ♯     ++  prefix ♯     |
| 2 | | pfxccat1 11173 |
. . . . . 6
  Word
Word    ++  prefix ♯     |
| 3 | | oveq2 5964 |
. . . . . . 7
 ♯  ♯    ++  prefix ♯     ++  prefix ♯     |
| 4 | | pfxccat1 11173 |
. . . . . . 7
  Word
Word    ++  prefix ♯     |
| 5 | 3, 4 | sylan9eqr 2261 |
. . . . . 6
   Word
Word  ♯  ♯     ++  prefix ♯     |
| 6 | 2, 5 | eqeqan12d 2222 |
. . . . 5
   Word
Word    Word Word  ♯  ♯       ++  prefix ♯     ++  prefix ♯  
   |
| 7 | 1, 6 | imbitrid 154 |
. . . 4
   Word
Word    Word Word  ♯  ♯      ++   ++ 
   |
| 8 | 7 | 3impb 1202 |
. . 3
   Word
Word   Word Word 
♯  ♯     ++   ++ 
   |
| 9 | | simpr 110 |
. . . . . 6
    Word Word 
 Word Word  ♯  ♯    ++
  ++    ++   ++    |
| 10 | | simpl3 1005 |
. . . . . . 7
    Word Word 
 Word Word  ♯  ♯    ++
  ++   ♯  ♯    |
| 11 | 9 | fveq2d 5592 |
. . . . . . . 8
    Word Word 
 Word Word  ♯  ♯    ++
  ++   ♯  ++   ♯  ++     |
| 12 | | simpl1 1003 |
. . . . . . . . 9
    Word Word 
 Word Word  ♯  ♯    ++
  ++   
Word Word    |
| 13 | | ccatlen 11069 |
. . . . . . . . 9
  Word
Word  ♯  ++    ♯  ♯     |
| 14 | 12, 13 | syl 14 |
. . . . . . . 8
    Word Word 
 Word Word  ♯  ♯    ++
  ++   ♯  ++    ♯  ♯     |
| 15 | | simpl2 1004 |
. . . . . . . . 9
    Word Word 
 Word Word  ♯  ♯    ++
  ++   
Word Word    |
| 16 | | ccatlen 11069 |
. . . . . . . . 9
  Word
Word  ♯  ++    ♯  ♯     |
| 17 | 15, 16 | syl 14 |
. . . . . . . 8
    Word Word 
 Word Word  ♯  ♯    ++
  ++   ♯  ++    ♯  ♯     |
| 18 | 11, 14, 17 | 3eqtr3d 2247 |
. . . . . . 7
    Word Word 
 Word Word  ♯  ♯    ++
  ++    ♯  ♯    ♯  ♯     |
| 19 | 10, 18 | opeq12d 3832 |
. . . . . 6
    Word Word 
 Word Word  ♯  ♯    ++
  ++    ♯    ♯  ♯     ♯    ♯  ♯      |
| 20 | 9, 19 | oveq12d 5974 |
. . . . 5
    Word Word 
 Word Word  ♯  ♯    ++
  ++     ++  substr  ♯    ♯  ♯       ++  substr  ♯    ♯  ♯       |
| 21 | | swrdccat2 11142 |
. . . . . 6
  Word
Word    ++  substr  ♯    ♯  ♯       |
| 22 | 12, 21 | syl 14 |
. . . . 5
    Word Word 
 Word Word  ♯  ♯    ++
  ++     ++  substr  ♯    ♯  ♯       |
| 23 | | swrdccat2 11142 |
. . . . . 6
  Word
Word    ++  substr  ♯    ♯  ♯       |
| 24 | 15, 23 | syl 14 |
. . . . 5
    Word Word 
 Word Word  ♯  ♯    ++
  ++     ++  substr  ♯    ♯  ♯       |
| 25 | 20, 22, 24 | 3eqtr3d 2247 |
. . . 4
    Word Word 
 Word Word  ♯  ♯    ++
  ++     |
| 26 | 25 | ex 115 |
. . 3
   Word
Word   Word Word 
♯  ♯     ++   ++ 
   |
| 27 | 8, 26 | jcad 307 |
. 2
   Word
Word   Word Word 
♯  ♯     ++   ++ 

    |
| 28 | | oveq12 5965 |
. 2
 
  ++   ++    |
| 29 | 27, 28 | impbid1 142 |
1
   Word
Word   Word Word 
♯  ♯     ++   ++       |