| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							4thatlem.ph | 
							 |-  ( ph <-> ( ( ( K e. HL /\ W e. H ) /\ ( P e. A /\ -. P .<_ W ) /\ ( Q e. A /\ -. Q .<_ W ) ) /\ ( S e. A /\ ( R e. A /\ -. R .<_ W /\ ( P .\/ R ) = ( Q .\/ R ) ) /\ ( T e. A /\ ( U .\/ T ) = ( V .\/ T ) ) ) /\ ( P =/= Q /\ -. S .<_ ( P .\/ Q ) ) ) )  | 
						
						
							| 2 | 
							
								
							 | 
							4thatlem0.l | 
							 |-  .<_ = ( le ` K )  | 
						
						
							| 3 | 
							
								
							 | 
							4thatlem0.j | 
							 |-  .\/ = ( join ` K )  | 
						
						
							| 4 | 
							
								
							 | 
							4thatlem0.m | 
							 |-  ./\ = ( meet ` K )  | 
						
						
							| 5 | 
							
								
							 | 
							4thatlem0.a | 
							 |-  A = ( Atoms ` K )  | 
						
						
							| 6 | 
							
								
							 | 
							4thatlem0.h | 
							 |-  H = ( LHyp ` K )  | 
						
						
							| 7 | 
							
								
							 | 
							4thatlem0.u | 
							 |-  U = ( ( P .\/ Q ) ./\ W )  | 
						
						
							| 8 | 
							
								
							 | 
							4thatlem0.v | 
							 |-  V = ( ( P .\/ S ) ./\ W )  | 
						
						
							| 9 | 
							
								
							 | 
							eqid | 
							 |-  ( Base ` K ) = ( Base ` K )  | 
						
						
							| 10 | 
							
								1
							 | 
							4atexlemkl | 
							 |-  ( ph -> K e. Lat )  | 
						
						
							| 11 | 
							
								1
							 | 
							4atexlemt | 
							 |-  ( ph -> T e. A )  | 
						
						
							| 12 | 
							
								9 5
							 | 
							atbase | 
							 |-  ( T e. A -> T e. ( Base ` K ) )  | 
						
						
							| 13 | 
							
								11 12
							 | 
							syl | 
							 |-  ( ph -> T e. ( Base ` K ) )  | 
						
						
							| 14 | 
							
								1
							 | 
							4atexlemk | 
							 |-  ( ph -> K e. HL )  | 
						
						
							| 15 | 
							
								1 2 3 4 5 6 7
							 | 
							4atexlemu | 
							 |-  ( ph -> U e. A )  | 
						
						
							| 16 | 
							
								1 2 3 4 5 6 7 8
							 | 
							4atexlemv | 
							 |-  ( ph -> V e. A )  | 
						
						
							| 17 | 
							
								9 3 5
							 | 
							hlatjcl | 
							 |-  ( ( K e. HL /\ U e. A /\ V e. A ) -> ( U .\/ V ) e. ( Base ` K ) )  | 
						
						
							| 18 | 
							
								14 15 16 17
							 | 
							syl3anc | 
							 |-  ( ph -> ( U .\/ V ) e. ( Base ` K ) )  | 
						
						
							| 19 | 
							
								1 6
							 | 
							4atexlemwb | 
							 |-  ( ph -> W e. ( Base ` K ) )  | 
						
						
							| 20 | 
							
								1
							 | 
							4atexlemkc | 
							 |-  ( ph -> K e. CvLat )  | 
						
						
							| 21 | 
							
								1 2 3 4 5 6 7 8
							 | 
							4atexlemunv | 
							 |-  ( ph -> U =/= V )  | 
						
						
							| 22 | 
							
								1
							 | 
							4atexlemutvt | 
							 |-  ( ph -> ( U .\/ T ) = ( V .\/ T ) )  | 
						
						
							| 23 | 
							
								5 2 3
							 | 
							cvlsupr4 | 
							 |-  ( ( K e. CvLat /\ ( U e. A /\ V e. A /\ T e. A ) /\ ( U =/= V /\ ( U .\/ T ) = ( V .\/ T ) ) ) -> T .<_ ( U .\/ V ) )  | 
						
						
							| 24 | 
							
								20 15 16 11 21 22 23
							 | 
							syl132anc | 
							 |-  ( ph -> T .<_ ( U .\/ V ) )  | 
						
						
							| 25 | 
							
								1
							 | 
							4atexlemp | 
							 |-  ( ph -> P e. A )  | 
						
						
							| 26 | 
							
								1
							 | 
							4atexlemq | 
							 |-  ( ph -> Q e. A )  | 
						
						
							| 27 | 
							
								9 3 5
							 | 
							hlatjcl | 
							 |-  ( ( K e. HL /\ P e. A /\ Q e. A ) -> ( P .\/ Q ) e. ( Base ` K ) )  | 
						
						
							| 28 | 
							
								14 25 26 27
							 | 
							syl3anc | 
							 |-  ( ph -> ( P .\/ Q ) e. ( Base ` K ) )  | 
						
						
							| 29 | 
							
								9 2 4
							 | 
							latmle2 | 
							 |-  ( ( K e. Lat /\ ( P .\/ Q ) e. ( Base ` K ) /\ W e. ( Base ` K ) ) -> ( ( P .\/ Q ) ./\ W ) .<_ W )  | 
						
						
							| 30 | 
							
								10 28 19 29
							 | 
							syl3anc | 
							 |-  ( ph -> ( ( P .\/ Q ) ./\ W ) .<_ W )  | 
						
						
							| 31 | 
							
								7 30
							 | 
							eqbrtrid | 
							 |-  ( ph -> U .<_ W )  | 
						
						
							| 32 | 
							
								1 3 5
							 | 
							4atexlempsb | 
							 |-  ( ph -> ( P .\/ S ) e. ( Base ` K ) )  | 
						
						
							| 33 | 
							
								9 2 4
							 | 
							latmle2 | 
							 |-  ( ( K e. Lat /\ ( P .\/ S ) e. ( Base ` K ) /\ W e. ( Base ` K ) ) -> ( ( P .\/ S ) ./\ W ) .<_ W )  | 
						
						
							| 34 | 
							
								10 32 19 33
							 | 
							syl3anc | 
							 |-  ( ph -> ( ( P .\/ S ) ./\ W ) .<_ W )  | 
						
						
							| 35 | 
							
								8 34
							 | 
							eqbrtrid | 
							 |-  ( ph -> V .<_ W )  | 
						
						
							| 36 | 
							
								9 5
							 | 
							atbase | 
							 |-  ( U e. A -> U e. ( Base ` K ) )  | 
						
						
							| 37 | 
							
								15 36
							 | 
							syl | 
							 |-  ( ph -> U e. ( Base ` K ) )  | 
						
						
							| 38 | 
							
								9 5
							 | 
							atbase | 
							 |-  ( V e. A -> V e. ( Base ` K ) )  | 
						
						
							| 39 | 
							
								16 38
							 | 
							syl | 
							 |-  ( ph -> V e. ( Base ` K ) )  | 
						
						
							| 40 | 
							
								9 2 3
							 | 
							latjle12 | 
							 |-  ( ( K e. Lat /\ ( U e. ( Base ` K ) /\ V e. ( Base ` K ) /\ W e. ( Base ` K ) ) ) -> ( ( U .<_ W /\ V .<_ W ) <-> ( U .\/ V ) .<_ W ) )  | 
						
						
							| 41 | 
							
								10 37 39 19 40
							 | 
							syl13anc | 
							 |-  ( ph -> ( ( U .<_ W /\ V .<_ W ) <-> ( U .\/ V ) .<_ W ) )  | 
						
						
							| 42 | 
							
								31 35 41
							 | 
							mpbi2and | 
							 |-  ( ph -> ( U .\/ V ) .<_ W )  | 
						
						
							| 43 | 
							
								9 2 10 13 18 19 24 42
							 | 
							lattrd | 
							 |-  ( ph -> T .<_ W )  |