| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mdsymlem1.1 |  |-  A e. CH | 
						
							| 2 |  | mdsymlem1.2 |  |-  B e. CH | 
						
							| 3 |  | mdsymlem1.3 |  |-  C = ( A vH p ) | 
						
							| 4 |  | ssin |  |-  ( ( r C_ B /\ r C_ C ) <-> r C_ ( B i^i C ) ) | 
						
							| 5 | 3 | sseq2i |  |-  ( r C_ C <-> r C_ ( A vH p ) ) | 
						
							| 6 | 5 | biimpi |  |-  ( r C_ C -> r C_ ( A vH p ) ) | 
						
							| 7 | 6 | adantl |  |-  ( ( r C_ B /\ r C_ C ) -> r C_ ( A vH p ) ) | 
						
							| 8 | 4 7 | sylbir |  |-  ( r C_ ( B i^i C ) -> r C_ ( A vH p ) ) | 
						
							| 9 | 1 | atcvat4i |  |-  ( ( r e. HAtoms /\ p e. HAtoms ) -> ( ( A =/= 0H /\ r C_ ( A vH p ) ) -> E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) ) ) | 
						
							| 10 | 9 | exp4b |  |-  ( r e. HAtoms -> ( p e. HAtoms -> ( A =/= 0H -> ( r C_ ( A vH p ) -> E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) ) ) ) ) | 
						
							| 11 | 10 | com34 |  |-  ( r e. HAtoms -> ( p e. HAtoms -> ( r C_ ( A vH p ) -> ( A =/= 0H -> E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) ) ) ) ) | 
						
							| 12 | 11 | com23 |  |-  ( r e. HAtoms -> ( r C_ ( A vH p ) -> ( p e. HAtoms -> ( A =/= 0H -> E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) ) ) ) ) | 
						
							| 13 | 12 | imp4b |  |-  ( ( r e. HAtoms /\ r C_ ( A vH p ) ) -> ( ( p e. HAtoms /\ A =/= 0H ) -> E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) ) ) | 
						
							| 14 | 8 13 | sylan2 |  |-  ( ( r e. HAtoms /\ r C_ ( B i^i C ) ) -> ( ( p e. HAtoms /\ A =/= 0H ) -> E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) ) ) | 
						
							| 15 | 14 | adantrr |  |-  ( ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) -> ( ( p e. HAtoms /\ A =/= 0H ) -> E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) ) ) | 
						
							| 16 | 15 | com12 |  |-  ( ( p e. HAtoms /\ A =/= 0H ) -> ( ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) -> E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) ) ) | 
						
							| 17 | 16 | adantlr |  |-  ( ( ( p e. HAtoms /\ -. ( B i^i C ) C_ A ) /\ A =/= 0H ) -> ( ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) -> E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) ) ) | 
						
							| 18 | 17 | adantlr |  |-  ( ( ( ( p e. HAtoms /\ -. ( B i^i C ) C_ A ) /\ p C_ ( A vH B ) ) /\ A =/= 0H ) -> ( ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) -> E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) ) ) | 
						
							| 19 | 18 | imp |  |-  ( ( ( ( ( p e. HAtoms /\ -. ( B i^i C ) C_ A ) /\ p C_ ( A vH B ) ) /\ A =/= 0H ) /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) ) | 
						
							| 20 |  | nssne2 |  |-  ( ( q C_ A /\ -. r C_ A ) -> q =/= r ) | 
						
							| 21 | 20 | adantrl |  |-  ( ( q C_ A /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) -> q =/= r ) | 
						
							| 22 |  | atnemeq0 |  |-  ( ( q e. HAtoms /\ r e. HAtoms ) -> ( q =/= r <-> ( q i^i r ) = 0H ) ) | 
						
							| 23 | 22 | ancoms |  |-  ( ( r e. HAtoms /\ q e. HAtoms ) -> ( q =/= r <-> ( q i^i r ) = 0H ) ) | 
						
							| 24 | 21 23 | imbitrid |  |-  ( ( r e. HAtoms /\ q e. HAtoms ) -> ( ( q C_ A /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) -> ( q i^i r ) = 0H ) ) | 
						
							| 25 | 24 | adantll |  |-  ( ( ( p e. HAtoms /\ r e. HAtoms ) /\ q e. HAtoms ) -> ( ( q C_ A /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) -> ( q i^i r ) = 0H ) ) | 
						
							| 26 | 25 | adantr |  |-  ( ( ( ( p e. HAtoms /\ r e. HAtoms ) /\ q e. HAtoms ) /\ r C_ ( p vH q ) ) -> ( ( q C_ A /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) -> ( q i^i r ) = 0H ) ) | 
						
							| 27 |  | atelch |  |-  ( p e. HAtoms -> p e. CH ) | 
						
							| 28 |  | atelch |  |-  ( q e. HAtoms -> q e. CH ) | 
						
							| 29 |  | chjcom |  |-  ( ( p e. CH /\ q e. CH ) -> ( p vH q ) = ( q vH p ) ) | 
						
							| 30 | 27 28 29 | syl2an |  |-  ( ( p e. HAtoms /\ q e. HAtoms ) -> ( p vH q ) = ( q vH p ) ) | 
						
							| 31 | 30 | adantlr |  |-  ( ( ( p e. HAtoms /\ r e. HAtoms ) /\ q e. HAtoms ) -> ( p vH q ) = ( q vH p ) ) | 
						
							| 32 | 31 | sseq2d |  |-  ( ( ( p e. HAtoms /\ r e. HAtoms ) /\ q e. HAtoms ) -> ( r C_ ( p vH q ) <-> r C_ ( q vH p ) ) ) | 
						
							| 33 |  | atexch |  |-  ( ( q e. CH /\ r e. HAtoms /\ p e. HAtoms ) -> ( ( r C_ ( q vH p ) /\ ( q i^i r ) = 0H ) -> p C_ ( q vH r ) ) ) | 
						
							| 34 | 28 33 | syl3an1 |  |-  ( ( q e. HAtoms /\ r e. HAtoms /\ p e. HAtoms ) -> ( ( r C_ ( q vH p ) /\ ( q i^i r ) = 0H ) -> p C_ ( q vH r ) ) ) | 
						
							| 35 | 34 | 3com13 |  |-  ( ( p e. HAtoms /\ r e. HAtoms /\ q e. HAtoms ) -> ( ( r C_ ( q vH p ) /\ ( q i^i r ) = 0H ) -> p C_ ( q vH r ) ) ) | 
						
							| 36 | 35 | 3expa |  |-  ( ( ( p e. HAtoms /\ r e. HAtoms ) /\ q e. HAtoms ) -> ( ( r C_ ( q vH p ) /\ ( q i^i r ) = 0H ) -> p C_ ( q vH r ) ) ) | 
						
							| 37 | 36 | expd |  |-  ( ( ( p e. HAtoms /\ r e. HAtoms ) /\ q e. HAtoms ) -> ( r C_ ( q vH p ) -> ( ( q i^i r ) = 0H -> p C_ ( q vH r ) ) ) ) | 
						
							| 38 | 32 37 | sylbid |  |-  ( ( ( p e. HAtoms /\ r e. HAtoms ) /\ q e. HAtoms ) -> ( r C_ ( p vH q ) -> ( ( q i^i r ) = 0H -> p C_ ( q vH r ) ) ) ) | 
						
							| 39 | 38 | imp |  |-  ( ( ( ( p e. HAtoms /\ r e. HAtoms ) /\ q e. HAtoms ) /\ r C_ ( p vH q ) ) -> ( ( q i^i r ) = 0H -> p C_ ( q vH r ) ) ) | 
						
							| 40 | 26 39 | syld |  |-  ( ( ( ( p e. HAtoms /\ r e. HAtoms ) /\ q e. HAtoms ) /\ r C_ ( p vH q ) ) -> ( ( q C_ A /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) -> p C_ ( q vH r ) ) ) | 
						
							| 41 | 40 | expd |  |-  ( ( ( ( p e. HAtoms /\ r e. HAtoms ) /\ q e. HAtoms ) /\ r C_ ( p vH q ) ) -> ( q C_ A -> ( ( r C_ ( B i^i C ) /\ -. r C_ A ) -> p C_ ( q vH r ) ) ) ) | 
						
							| 42 | 41 | exp31 |  |-  ( ( p e. HAtoms /\ r e. HAtoms ) -> ( q e. HAtoms -> ( r C_ ( p vH q ) -> ( q C_ A -> ( ( r C_ ( B i^i C ) /\ -. r C_ A ) -> p C_ ( q vH r ) ) ) ) ) ) | 
						
							| 43 | 42 | com24 |  |-  ( ( p e. HAtoms /\ r e. HAtoms ) -> ( q C_ A -> ( r C_ ( p vH q ) -> ( q e. HAtoms -> ( ( r C_ ( B i^i C ) /\ -. r C_ A ) -> p C_ ( q vH r ) ) ) ) ) ) | 
						
							| 44 | 43 | impd |  |-  ( ( p e. HAtoms /\ r e. HAtoms ) -> ( ( q C_ A /\ r C_ ( p vH q ) ) -> ( q e. HAtoms -> ( ( r C_ ( B i^i C ) /\ -. r C_ A ) -> p C_ ( q vH r ) ) ) ) ) | 
						
							| 45 | 44 | com24 |  |-  ( ( p e. HAtoms /\ r e. HAtoms ) -> ( ( r C_ ( B i^i C ) /\ -. r C_ A ) -> ( q e. HAtoms -> ( ( q C_ A /\ r C_ ( p vH q ) ) -> p C_ ( q vH r ) ) ) ) ) | 
						
							| 46 | 45 | imp4b |  |-  ( ( ( p e. HAtoms /\ r e. HAtoms ) /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) -> ( ( q e. HAtoms /\ ( q C_ A /\ r C_ ( p vH q ) ) ) -> p C_ ( q vH r ) ) ) | 
						
							| 47 | 46 | anasss |  |-  ( ( p e. HAtoms /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> ( ( q e. HAtoms /\ ( q C_ A /\ r C_ ( p vH q ) ) ) -> p C_ ( q vH r ) ) ) | 
						
							| 48 |  | simprl |  |-  ( ( q e. HAtoms /\ ( q C_ A /\ r C_ ( p vH q ) ) ) -> q C_ A ) | 
						
							| 49 | 48 | a1i |  |-  ( ( p e. HAtoms /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> ( ( q e. HAtoms /\ ( q C_ A /\ r C_ ( p vH q ) ) ) -> q C_ A ) ) | 
						
							| 50 |  | simpl |  |-  ( ( r C_ B /\ r C_ C ) -> r C_ B ) | 
						
							| 51 | 4 50 | sylbir |  |-  ( r C_ ( B i^i C ) -> r C_ B ) | 
						
							| 52 | 51 | ad2antrl |  |-  ( ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) -> r C_ B ) | 
						
							| 53 | 52 | adantl |  |-  ( ( p e. HAtoms /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> r C_ B ) | 
						
							| 54 | 49 53 | jctird |  |-  ( ( p e. HAtoms /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> ( ( q e. HAtoms /\ ( q C_ A /\ r C_ ( p vH q ) ) ) -> ( q C_ A /\ r C_ B ) ) ) | 
						
							| 55 | 47 54 | jcad |  |-  ( ( p e. HAtoms /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> ( ( q e. HAtoms /\ ( q C_ A /\ r C_ ( p vH q ) ) ) -> ( p C_ ( q vH r ) /\ ( q C_ A /\ r C_ B ) ) ) ) | 
						
							| 56 | 55 | expd |  |-  ( ( p e. HAtoms /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> ( q e. HAtoms -> ( ( q C_ A /\ r C_ ( p vH q ) ) -> ( p C_ ( q vH r ) /\ ( q C_ A /\ r C_ B ) ) ) ) ) | 
						
							| 57 | 56 | adantlr |  |-  ( ( ( p e. HAtoms /\ -. ( B i^i C ) C_ A ) /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> ( q e. HAtoms -> ( ( q C_ A /\ r C_ ( p vH q ) ) -> ( p C_ ( q vH r ) /\ ( q C_ A /\ r C_ B ) ) ) ) ) | 
						
							| 58 | 57 | adantlr |  |-  ( ( ( ( p e. HAtoms /\ -. ( B i^i C ) C_ A ) /\ p C_ ( A vH B ) ) /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> ( q e. HAtoms -> ( ( q C_ A /\ r C_ ( p vH q ) ) -> ( p C_ ( q vH r ) /\ ( q C_ A /\ r C_ B ) ) ) ) ) | 
						
							| 59 | 58 | adantlr |  |-  ( ( ( ( ( p e. HAtoms /\ -. ( B i^i C ) C_ A ) /\ p C_ ( A vH B ) ) /\ A =/= 0H ) /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> ( q e. HAtoms -> ( ( q C_ A /\ r C_ ( p vH q ) ) -> ( p C_ ( q vH r ) /\ ( q C_ A /\ r C_ B ) ) ) ) ) | 
						
							| 60 | 59 | reximdvai |  |-  ( ( ( ( ( p e. HAtoms /\ -. ( B i^i C ) C_ A ) /\ p C_ ( A vH B ) ) /\ A =/= 0H ) /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> ( E. q e. HAtoms ( q C_ A /\ r C_ ( p vH q ) ) -> E. q e. HAtoms ( p C_ ( q vH r ) /\ ( q C_ A /\ r C_ B ) ) ) ) | 
						
							| 61 | 19 60 | mpd |  |-  ( ( ( ( ( p e. HAtoms /\ -. ( B i^i C ) C_ A ) /\ p C_ ( A vH B ) ) /\ A =/= 0H ) /\ ( r e. HAtoms /\ ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) -> E. q e. HAtoms ( p C_ ( q vH r ) /\ ( q C_ A /\ r C_ B ) ) ) | 
						
							| 62 |  | chjcl |  |-  ( ( A e. CH /\ p e. CH ) -> ( A vH p ) e. CH ) | 
						
							| 63 | 1 62 | mpan |  |-  ( p e. CH -> ( A vH p ) e. CH ) | 
						
							| 64 | 3 63 | eqeltrid |  |-  ( p e. CH -> C e. CH ) | 
						
							| 65 |  | chincl |  |-  ( ( B e. CH /\ C e. CH ) -> ( B i^i C ) e. CH ) | 
						
							| 66 | 2 64 65 | sylancr |  |-  ( p e. CH -> ( B i^i C ) e. CH ) | 
						
							| 67 | 27 66 | syl |  |-  ( p e. HAtoms -> ( B i^i C ) e. CH ) | 
						
							| 68 |  | chrelat2 |  |-  ( ( ( B i^i C ) e. CH /\ A e. CH ) -> ( -. ( B i^i C ) C_ A <-> E. r e. HAtoms ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) | 
						
							| 69 | 67 1 68 | sylancl |  |-  ( p e. HAtoms -> ( -. ( B i^i C ) C_ A <-> E. r e. HAtoms ( r C_ ( B i^i C ) /\ -. r C_ A ) ) ) | 
						
							| 70 | 69 | biimpa |  |-  ( ( p e. HAtoms /\ -. ( B i^i C ) C_ A ) -> E. r e. HAtoms ( r C_ ( B i^i C ) /\ -. r C_ A ) ) | 
						
							| 71 | 70 | ad2antrr |  |-  ( ( ( ( p e. HAtoms /\ -. ( B i^i C ) C_ A ) /\ p C_ ( A vH B ) ) /\ A =/= 0H ) -> E. r e. HAtoms ( r C_ ( B i^i C ) /\ -. r C_ A ) ) | 
						
							| 72 | 61 71 | reximddv |  |-  ( ( ( ( p e. HAtoms /\ -. ( B i^i C ) C_ A ) /\ p C_ ( A vH B ) ) /\ A =/= 0H ) -> E. r e. HAtoms E. q e. HAtoms ( p C_ ( q vH r ) /\ ( q C_ A /\ r C_ B ) ) ) |