| Step | Hyp | Ref
 | Expression | 
| 1 |   | frecsuc.1 | 
. . . . . . . 8
      FRec        | 
| 2 |   | frecsuc.2 | 
. . . . . . . 8
           Funs   | 
| 3 |   | frecsuc.3 | 
. . . . . . . 8
                | 
| 4 |   | frecsuc.4 | 
. . . . . . . 8
                  | 
| 5 | 1, 2, 3, 4 | fnfrec 6321 | 
. . . . . . 7
           Nn   | 
| 6 |   | fnfun 5182 | 
. . . . . . 7
       Nn        | 
| 7 | 5, 6 | syl 15 | 
. . . . . 6
            | 
| 8 |   | frecsuc.5 | 
. . . . . . 7
           Nn   | 
| 9 | 1, 2, 3, 4 | dmfrec 6317 | 
. . . . . . 7
             Nn   | 
| 10 | 8, 9 | eleqtrrd 2430 | 
. . . . . 6
                | 
| 11 |   | funfvop 5401 | 
. . . . . 6
                        
            | 
| 12 | 7, 10, 11 | syl2anc 642 | 
. . . . 5
                       | 
| 13 |   | eqid 2353 | 
. . . . . 6
       1c   
     1c  | 
| 14 |   | peano2 4404 | 
. . . . . . . 8
       Nn       
1c 
  Nn   | 
| 15 | 8, 14 | syl 15 | 
. . . . . . 7
           
1c 
  Nn   | 
| 16 |   | addceq1 4384 | 
. . . . . . . . 9
                1c         1c   | 
| 17 | 16 | eqeq2d 2364 | 
. . . . . . . 8
               
     1c             1c    | 
| 18 |   | eqeq1 2359 | 
. . . . . . . 8
            1c             
1c 
 
     1c   
     1c    | 
| 19 |   | mptv 5719 | 
. . . . . . . 8
                1c                        1c   | 
| 20 | 17, 18, 19 | brabg 4707 | 
. . . . . . 7
        Nn        1c    Nn                     1c       1c        
1c 
       1c    | 
| 21 | 8, 15, 20 | syl2anc 642 | 
. . . . . 6
                       1c       1c        
1c 
       1c    | 
| 22 | 13, 21 | mpbiri 224 | 
. . . . 5
                      1c      
1c   | 
| 23 |   | elfunsi 5832 | 
. . . . . . . 8
       Funs        | 
| 24 | 2, 23 | syl 15 | 
. . . . . . 7
            | 
| 25 | 3 | snssd 3854 | 
. . . . . . . . 9
                  | 
| 26 | 4, 25 | unssd 3440 | 
. . . . . . . 8
                          | 
| 27 | 1 | frecxpg 6316 | 
. . . . . . . . . . . 12
       Funs         Nn                 | 
| 28 | 2, 27 | syl 15 | 
. . . . . . . . . . 11
          
  Nn                 | 
| 29 |   | rnss 4960 | 
. . . . . . . . . . 11
        
Nn                            Nn                 | 
| 30 | 28, 29 | syl 15 | 
. . . . . . . . . 10
                 Nn                 | 
| 31 |   | rnxpss 5054 | 
. . . . . . . . . 10
      Nn                              | 
| 32 | 30, 31 | syl6ss 3285 | 
. . . . . . . . 9
                          | 
| 33 |   | fvelrn 5414 | 
. . . . . . . . . 10
                                  | 
| 34 | 7, 10, 33 | syl2anc 642 | 
. . . . . . . . 9
              
     | 
| 35 | 32, 34 | sseldd 3275 | 
. . . . . . . 8
              
             | 
| 36 | 26, 35 | sseldd 3275 | 
. . . . . . 7
              
     | 
| 37 |   | funfvop 5401 | 
. . . . . . 7
                      
                          | 
| 38 | 24, 36, 37 | syl2anc 642 | 
. . . . . 6
                               | 
| 39 |   | df-br 4641 | 
. . . . . 6
                                             | 
| 40 | 38, 39 | sylibr 203 | 
. . . . 5
                        | 
| 41 |   | breq1 4643 | 
. . . . . . 7
                       PProd                1c   
       
1c                           PProd             
 
1c            1c                | 
| 42 |   | qrpprod 5837 | 
. . . . . . 7
      
       PProd                1c   
       
1c                             
 
1c       1c                      | 
| 43 | 41, 42 | syl6bb 252 | 
. . . . . 6
                       PProd                1c   
       
1c                             
 
1c       1c                       | 
| 44 | 43 | rspcev 2956 | 
. . . . 5
                                    
1c       1c                          
      PProd    
        
 
1c            1c               | 
| 45 | 12, 22, 40, 44 | syl12anc 1180 | 
. . . 4
                PProd    
        
 
1c            1c               | 
| 46 | 45 | olcd 382 | 
. . 3
              1c  
               0c                 PProd               
1c            1c                | 
| 47 |   | snex 4112 | 
. . . 4
    0c          | 
| 48 |   | csucex 6260 | 
. . . . 5
                1c       | 
| 49 |   | pprodexg 5838 | 
. . . . 5
               
 
1c             Funs     PProd                1c   
        | 
| 50 | 48, 2, 49 | sylancr 644 | 
. . . 4
       PProd    
        
 
1c        
   | 
| 51 |   | df-frec 6311 | 
. . . . . 6
  FRec         
 Clos1    0c       PProd               
1c        | 
| 52 | 1, 51 | eqtri 2373 | 
. . . . 5
       Clos1
   0c       PProd                1c   
    | 
| 53 | 52 | clos1basesucg 5885 | 
. . . 4
      0c            PProd             
 
1c        
            1c  
                        1c                  0c                 PProd               
1c            1c                 | 
| 54 | 47, 50, 53 | sylancr 644 | 
. . 3
              1c  
                        1c                  0c                 PProd               
1c            1c                 | 
| 55 | 46, 54 | mpbird 223 | 
. 2
             1c                   | 
| 56 |   | fnopfvb 5360 | 
. . 3
        Nn        1c    Nn           
 
1c                       1c                    | 
| 57 | 5, 15, 56 | syl2anc 642 | 
. 2
             
 
1c                       1c                    | 
| 58 | 55, 57 | mpbird 223 | 
1
               1c                |