Proof of Theorem latdir
| Step | Hyp | Ref
| Expression |
| 1 | | posispre 14582 |
. . . . 5

Poset Preset  |
| 2 | 1 | adantr 425 |
. . . 4
  Poset       supw      infw       Preset  |
| 3 | | zfpair 3522 |
. . . . . . . . . . . . 13
    |
| 4 | | eqid 1884 |
. . . . . . . . . . . . . . . 16
 |
| 5 | 4 | supaub 14615 |
. . . . . . . . . . . . . . 15
  Poset    
supw      
supw      ub       |
| 6 | 5 | 3exp 1066 |
. . . . . . . . . . . . . 14

Poset      
supw      supw      ub         |
| 7 | 6 | com3l 38 |
. . . . . . . . . . . . 13
      supw      Poset 
supw      ub         |
| 8 | 3, 7 | ax-mp 7 |
. . . . . . . . . . . 12
 
supw     
Poset  supw      ub        |
| 9 | | eleq1 1957 |
. . . . . . . . . . . . . 14
  supw       ub  
   supw      ub  
     |
| 10 | 9 | rcla4ev 2381 |
. . . . . . . . . . . . 13
   supw     
supw      ub        ub  
    |
| 11 | 10 | ex 402 |
. . . . . . . . . . . 12
 
supw      
supw      ub       ub        |
| 12 | 8, 11 | syld 30 |
. . . . . . . . . . 11
 
supw     
Poset   ub  
     |
| 13 | 12 | adantr 425 |
. . . . . . . . . 10
   supw     
infw       Poset 
 ub        |
| 14 | 13 | com12 14 |
. . . . . . . . 9

Poset   
supw      infw      
 ub        |
| 15 | 14 | adantr 425 |
. . . . . . . 8
  Poset

  
supw      infw      
 ub        |
| 16 | 15 | ralimdvaa 2171 |
. . . . . . 7

Poset      supw     
infw          ub        |
| 17 | 16 | adantr 425 |
. . . . . 6
  Poset

 
   supw     
infw          ub        |
| 18 | 17 | ralimdvaa 2171 |
. . . . 5

Poset        supw      infw        
 
 ub        |
| 19 | 18 | imp 377 |
. . . 4
  Poset       supw      infw       
 
   ub       |
| 20 | 2, 19 | jca 310 |
. . 3
  Poset       supw      infw        Preset

 
   ub        |
| 21 | 4 | isla 10010 |
. . 3
 Lat
 Poset   
  
supw      infw         |
| 22 | 4 | isdir2 14640 |
. . 3
 Dir
 Preset   
 
 ub        |
| 23 | 20, 21, 22 | 3imtr4i 236 |
. 2
 Lat
Dir |
| 24 | 23 | ssriv 2621 |
1
Lat Dir |