Proof of Theorem nchoicelem8
| Step | Hyp | Ref
 | Expression | 
| 1 |   | ce0lenc1 6240 | 
. . . 4
       NC       ↑c
0c 
  NC      c Nc 1c   | 
| 2 | 1 | notbid 285 | 
. . 3
       NC         ↑c
0c 
  NC        c Nc 1c   | 
| 3 | 2 | adantl 452 | 
. 2
      c We NC       NC          
↑c 0c    NC        c Nc 1c   | 
| 4 |   | df-we 5907 | 
. . . . . . . . . 10
  We     Or   Fr   | 
| 5 | 4 | breqi 4646 | 
. . . . . . . . 9
     c We
NC    c   Or   Fr   NC   | 
| 6 |   | brin 4694 | 
. . . . . . . . 9
     c   Or   Fr   NC      c Or NC    c Fr NC    | 
| 7 | 5, 6 | bitri 240 | 
. . . . . . . 8
     c We
NC      c Or NC    c Fr NC    | 
| 8 |   | sopc 5935 | 
. . . . . . . . . 10
     c Or
NC      c Po NC    c Connex NC    | 
| 9 | 8 | simprbi 450 | 
. . . . . . . . 9
     c Or
NC    c Connex NC   | 
| 10 | 9 | adantr 451 | 
. . . . . . . 8
      c Or NC    c Fr NC      c Connex NC   | 
| 11 | 7, 10 | sylbi 187 | 
. . . . . . 7
     c We
NC    c Connex NC   | 
| 12 |   | simpl 443 | 
. . . . . . . 8
      c Connex NC       NC      c Connex NC   | 
| 13 |   | simpr 447 | 
. . . . . . . 8
      c Connex NC       NC         NC   | 
| 14 |   | 1cex 4143 | 
. . . . . . . . . 10
 
1c  
  | 
| 15 | 14 | ncelncsi 6122 | 
. . . . . . . . 9
  Nc 1c   NC | 
| 16 | 15 | a1i 10 | 
. . . . . . . 8
      c Connex NC       NC     Nc 1c   NC   | 
| 17 | 12, 13, 16 | connexd 5932 | 
. . . . . . 7
      c Connex NC       NC         c Nc 1c
  Nc 1c  c     | 
| 18 | 11, 17 | sylan 457 | 
. . . . . 6
      c We NC       NC         c Nc 1c
  Nc 1c  c     | 
| 19 | 18 | ord 366 | 
. . . . 5
      c We NC       NC           c Nc 1c
  Nc 1c  c     | 
| 20 |   | id 19 | 
. . . . . . . 8
    Nc 1c       Nc 1c      | 
| 21 |   | nclecid 6198 | 
. . . . . . . . 9
    Nc 1c   NC   Nc 1c  c Nc
1c  | 
| 22 | 15, 21 | ax-mp 5 | 
. . . . . . . 8
  Nc 1c  c Nc
1c | 
| 23 | 20, 22 | syl6eqbrr 4678 | 
. . . . . . 7
    Nc 1c          c Nc 1c  | 
| 24 | 23 | necon3bi 2558 | 
. . . . . 6
        c Nc 1c
  Nc 1c      | 
| 25 | 24 | a1i 10 | 
. . . . 5
      c We NC       NC           c Nc 1c
  Nc 1c       | 
| 26 | 19, 25 | jcad 519 | 
. . . 4
      c We NC       NC           c Nc 1c
    Nc
1c  c     Nc 1c        | 
| 27 | 7 | simplbi 446 | 
. . . . . . . . . . 11
     c We
NC    c Or NC   | 
| 28 | 8 | simplbi 446 | 
. . . . . . . . . . 11
     c Or
NC    c Po NC   | 
| 29 |   | df-partial 5903 | 
. . . . . . . . . . . . . 14
  Po      Ref   Trans     Antisym   | 
| 30 | 29 | breqi 4646 | 
. . . . . . . . . . . . 13
     c Po
NC    c   
Ref   Trans     Antisym   NC   | 
| 31 |   | brin 4694 | 
. . . . . . . . . . . . 13
     c    Ref   Trans     Antisym   NC      c  
Ref   Trans   NC    c Antisym NC    | 
| 32 | 30, 31 | bitri 240 | 
. . . . . . . . . . . 12
     c Po
NC      c  
Ref   Trans   NC    c Antisym NC    | 
| 33 | 32 | simprbi 450 | 
. . . . . . . . . . 11
     c Po
NC    c Antisym NC   | 
| 34 | 27, 28, 33 | 3syl 18 | 
. . . . . . . . . 10
     c We
NC    c Antisym NC   | 
| 35 | 34 | adantr 451 | 
. . . . . . . . 9
      c We NC       NC      c Antisym NC   | 
| 36 | 35 | adantr 451 | 
. . . . . . . 8
       c We NC       NC       Nc 1c  c        c Nc 1c      c Antisym NC   | 
| 37 | 15 | a1i 10 | 
. . . . . . . 8
       c We NC       NC       Nc 1c  c        c Nc 1c     Nc 1c
  NC   | 
| 38 |   | simplr 731 | 
. . . . . . . 8
       c We NC       NC       Nc 1c  c        c Nc 1c         NC   | 
| 39 |   | simprl 732 | 
. . . . . . . 8
       c We NC       NC       Nc 1c  c        c Nc 1c     Nc 1c
 c    | 
| 40 |   | simprr 733 | 
. . . . . . . 8
       c We NC       NC       Nc 1c  c        c Nc 1c        c Nc 1c  | 
| 41 | 36, 37, 38, 39, 40 | antid 5930 | 
. . . . . . 7
       c We NC       NC       Nc 1c  c        c Nc 1c     Nc 1c
     | 
| 42 | 41 | expr 598 | 
. . . . . 6
       c We NC       NC     Nc 1c  c          c Nc 1c
  Nc 1c       | 
| 43 | 42 | necon3ad 2553 | 
. . . . 5
       c We NC       NC     Nc 1c  c        Nc 1c            c Nc 1c   | 
| 44 | 43 | expimpd 586 | 
. . . 4
      c We NC       NC        Nc
1c  c     Nc 1c     
       c Nc
1c   | 
| 45 | 26, 44 | impbid 183 | 
. . 3
      c We NC       NC           c Nc 1c
 
  Nc 1c  c     Nc 1c        | 
| 46 |   | brltc 6115 | 
. . 3
    Nc 1c  c       Nc 1c  c     Nc
1c       | 
| 47 | 45, 46 | syl6bbr 254 | 
. 2
      c We NC       NC           c Nc 1c
 
Nc 1c  c     | 
| 48 | 3, 47 | bitrd 244 | 
1
      c We NC       NC          
↑c 0c    NC   Nc
1c  c     |