| Step | Hyp | Ref
| Expression |
| 1 | | coafval.o |
. 2
compa   |
| 2 | | fveq2 6191 |
. . . . . 6
 Nat  Nat    |
| 3 | | coafval.a |
. . . . . 6
Nat   |
| 4 | 2, 3 | syl6eqr 2674 |
. . . . 5
 Nat    |
| 5 | 4 | rabeqdv 3194 |
. . . . 5
  Nat  coda        
coda          |
| 6 | | fveq2 6191 |
. . . . . . . . 9
 comp  comp    |
| 7 | | coafval.x |
. . . . . . . . 9
comp   |
| 8 | 6, 7 | syl6eqr 2674 |
. . . . . . . 8
 comp   |
| 9 | 8 | oveqd 6667 |
. . . . . . 7
                comp   coda                 coda     |
| 10 | 9 | oveqd 6667 |
. . . . . 6
                      comp   coda                             coda           |
| 11 | 10 | oteq3d 4416 |
. . . . 5
        coda                        comp   coda                 coda                       coda            |
| 12 | 4, 5, 11 | mpt2eq123dv 6717 |
. . . 4
  Nat    Nat  coda               coda                        comp   coda              coda               coda                       coda             |
| 13 | | df-coa 16706 |
. . . 4
compa   Nat  
 Nat  coda               coda                        comp   coda             |
| 14 | | fvex 6201 |
. . . . . 6
Nat   |
| 15 | 3, 14 | eqeltri 2697 |
. . . . 5
 |
| 16 | 15 | rabex 4813 |
. . . . 5

coda         |
| 17 | 15, 16 | mpt2ex 7247 |
. . . 4
   coda               coda                       coda            |
| 18 | 12, 13, 17 | fvmpt 6282 |
. . 3
 compa     coda               coda                       coda             |
| 19 | 13 | dmmptss 5631 |
. . . . . . 7
compa  |
| 20 | 19 | sseli 3599 |
. . . . . 6

compa   |
| 21 | 20 | con3i 150 |
. . . . 5

compa |
| 22 | | ndmfv 6218 |
. . . . 5

compa compa    |
| 23 | 21, 22 | syl 17 |
. . . 4
 compa    |
| 24 | 3 | arwrcl 16694 |
. . . . . . . 8
   |
| 25 | 24 | con3i 150 |
. . . . . . 7
   |
| 26 | 25 | eq0rdv 3979 |
. . . . . 6
   |
| 27 | | eqidd 2623 |
. . . . . 6
  coda         coda          |
| 28 | | eqidd 2623 |
. . . . . 6
        coda                       coda                 coda                       coda            |
| 29 | 26, 27, 28 | mpt2eq123dv 6717 |
. . . . 5
   
coda               coda                       coda              coda               coda                       coda             |
| 30 | | mpt20 6725 |
. . . . 5
   coda               coda                       coda            |
| 31 | 29, 30 | syl6eq 2672 |
. . . 4
   
coda               coda                       coda             |
| 32 | 23, 31 | eqtr4d 2659 |
. . 3
 compa    
coda               coda                       coda             |
| 33 | 18, 32 | pm2.61i 176 |
. 2
compa     coda               coda                       coda            |
| 34 | 1, 33 | eqtri 2644 |
1
 

coda               coda                       coda            |