Proof of Theorem txcld
| Step | Hyp | Ref
| Expression |
| 1 | | xpss12 4089 |
. . . . . . . 8
  
  
       |
| 2 | 1 | ad2ant2r 445 |
. . . . . . 7
   
 

  
 

          |
| 3 | 2 | adantl 424 |
. . . . . 6
   Top
Top     

  
 

   
       |
| 4 | | txcld.1 |
. . . . . . . 8
    |
| 5 | | eqid 1884 |
. . . . . . . 8
   |
| 6 | | eqid 1884 |
. . . . . . . 8
   |
| 7 | 4, 5, 6 | txuni 8935 |
. . . . . . 7
  Top
Top        |
| 8 | 7 | adantr 425 |
. . . . . 6
   Top
Top     

  
 

          |
| 9 | 3, 8 | sseqtr4d 2654 |
. . . . 5
   Top
Top     

  
 

   
    |
| 10 | 9 | ex 402 |
. . . 4
  Top
Top      

  
 

        |
| 11 | 7 | adantr 425 |
. . . . . . . . . 10
   Top
Top      

         |
| 12 | 11 | difeq1d 2725 |
. . . . . . . . 9
   Top
Top      

           
     |
| 13 | | difxp 15690 |
. . . . . . . . 9
                          
 
    |
| 14 | 12, 13 | syl6eq 1944 |
. . . . . . . 8
   Top
Top      

                                 |
| 15 | 4 | txtop 8934 |
. . . . . . . . . 10
  Top
Top
Top |
| 16 | 15 | adantr 425 |
. . . . . . . . 9
   Top
Top      

  Top |
| 17 | 6 | topopn 8871 |
. . . . . . . . . . . . 13
 Top
   |
| 18 | 17 | ad2antlr 441 |
. . . . . . . . . . . 12
   Top
Top     
  |
| 19 | 4 | txopn 15913 |
. . . . . . . . . . . . 13
   Top
Top     
     
 
  |
| 20 | 19 | anassrs 489 |
. . . . . . . . . . . 12
    Top Top          
 
  |
| 21 | 18, 20 | mpdan 768 |
. . . . . . . . . . 11
   Top
Top             |
| 22 | 21 | adantrr 431 |
. . . . . . . . . 10
   Top
Top      

     
 
  |
| 23 | 5 | topopn 8871 |
. . . . . . . . . . . . 13
 Top
   |
| 24 | 23 | ad2antrr 440 |
. . . . . . . . . . . 12
   Top
Top     
  |
| 25 | 4 | txopn 15913 |
. . . . . . . . . . . . . 14
   Top
Top  
 

          |
| 26 | 25 | ancom2s 545 |
. . . . . . . . . . . . 13
   Top
Top     
          |
| 27 | 26 | anassrs 489 |
. . . . . . . . . . . 12
    Top Top               |
| 28 | 24, 27 | mpdan 768 |
. . . . . . . . . . 11
   Top
Top      
 
    |
| 29 | 28 | adantrl 430 |
. . . . . . . . . 10
   Top
Top      

          |
| 30 | | unopn 15835 |
. . . . . . . . . 10
  Top                  
 
 
 
     |
| 31 | 16, 22, 29, 30 | syl111anc 1100 |
. . . . . . . . 9
   Top
Top      

                  |
| 32 | 4 | txopn 15913 |
. . . . . . . . 9
   Top
Top      

     
 
    |
| 33 | | unopn 15835 |
. . . . . . . . 9
  Top                                          
 
     |
| 34 | 16, 31, 32, 33 | syl111anc 1100 |
. . . . . . . 8
   Top
Top      

                            |
| 35 | 14, 34 | eqeltrd 1971 |
. . . . . . 7
   Top
Top      

         |
| 36 | 35 | adantrll 436 |
. . . . . 6
   Top
Top     

             |
| 37 | 36 | adantrrl 438 |
. . . . 5
   Top
Top     

  
 

    

    |
| 38 | 37 | ex 402 |
. . . 4
  Top
Top      

  
 

          |
| 39 | 10, 38 | jcad 661 |
. . 3
  Top
Top      

  
 

       

      |
| 40 | 5 | iscld 8945 |
. . . 4
 Top

Clsd   
 
     |
| 41 | 6 | iscld 8945 |
. . . 4
 Top

Clsd   
 
     |
| 42 | 40, 41 | bi2anan9 694 |
. . 3
  Top
Top   Clsd  Clsd     
 

  
 

     |
| 43 | | eqid 1884 |
. . . . 5
   |
| 44 | 43 | iscld 8945 |
. . . 4
 Top
  
Clsd     
 
       |
| 45 | 15, 44 | syl 12 |
. . 3
  Top
Top    Clsd        
      |
| 46 | 39, 42, 45 | 3imtr4d 602 |
. 2
  Top
Top   Clsd  Clsd     Clsd     |
| 47 | 46 | imp 377 |
1
   Top
Top  Clsd  Clsd      Clsd    |