| Step | Hyp | Ref | Expression | 
						
							| 1 |  | atlelt.b |  |-  B = ( Base ` K ) | 
						
							| 2 |  | atlelt.l |  |-  .<_ = ( le ` K ) | 
						
							| 3 |  | atlelt.s |  |-  .< = ( lt ` K ) | 
						
							| 4 |  | atlelt.a |  |-  A = ( Atoms ` K ) | 
						
							| 5 |  | simp3r |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> Q .< X ) | 
						
							| 6 |  | breq1 |  |-  ( P = Q -> ( P .< X <-> Q .< X ) ) | 
						
							| 7 | 5 6 | syl5ibrcom |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> ( P = Q -> P .< X ) ) | 
						
							| 8 |  | simp1 |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> K e. HL ) | 
						
							| 9 |  | simp21 |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> P e. A ) | 
						
							| 10 |  | simp22 |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> Q e. A ) | 
						
							| 11 |  | eqid |  |-  ( join ` K ) = ( join ` K ) | 
						
							| 12 | 3 11 4 | atlt |  |-  ( ( K e. HL /\ P e. A /\ Q e. A ) -> ( P .< ( P ( join ` K ) Q ) <-> P =/= Q ) ) | 
						
							| 13 | 8 9 10 12 | syl3anc |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> ( P .< ( P ( join ` K ) Q ) <-> P =/= Q ) ) | 
						
							| 14 |  | simp3l |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> P .<_ X ) | 
						
							| 15 |  | simp23 |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> X e. B ) | 
						
							| 16 | 8 10 15 | 3jca |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> ( K e. HL /\ Q e. A /\ X e. B ) ) | 
						
							| 17 | 2 3 | pltle |  |-  ( ( K e. HL /\ Q e. A /\ X e. B ) -> ( Q .< X -> Q .<_ X ) ) | 
						
							| 18 | 16 5 17 | sylc |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> Q .<_ X ) | 
						
							| 19 |  | hllat |  |-  ( K e. HL -> K e. Lat ) | 
						
							| 20 | 19 | 3ad2ant1 |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> K e. Lat ) | 
						
							| 21 | 1 4 | atbase |  |-  ( P e. A -> P e. B ) | 
						
							| 22 | 9 21 | syl |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> P e. B ) | 
						
							| 23 | 1 4 | atbase |  |-  ( Q e. A -> Q e. B ) | 
						
							| 24 | 10 23 | syl |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> Q e. B ) | 
						
							| 25 | 1 2 11 | latjle12 |  |-  ( ( K e. Lat /\ ( P e. B /\ Q e. B /\ X e. B ) ) -> ( ( P .<_ X /\ Q .<_ X ) <-> ( P ( join ` K ) Q ) .<_ X ) ) | 
						
							| 26 | 20 22 24 15 25 | syl13anc |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> ( ( P .<_ X /\ Q .<_ X ) <-> ( P ( join ` K ) Q ) .<_ X ) ) | 
						
							| 27 | 14 18 26 | mpbi2and |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> ( P ( join ` K ) Q ) .<_ X ) | 
						
							| 28 |  | hlpos |  |-  ( K e. HL -> K e. Poset ) | 
						
							| 29 | 28 | 3ad2ant1 |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> K e. Poset ) | 
						
							| 30 | 1 11 | latjcl |  |-  ( ( K e. Lat /\ P e. B /\ Q e. B ) -> ( P ( join ` K ) Q ) e. B ) | 
						
							| 31 | 20 22 24 30 | syl3anc |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> ( P ( join ` K ) Q ) e. B ) | 
						
							| 32 | 1 2 3 | pltletr |  |-  ( ( K e. Poset /\ ( P e. B /\ ( P ( join ` K ) Q ) e. B /\ X e. B ) ) -> ( ( P .< ( P ( join ` K ) Q ) /\ ( P ( join ` K ) Q ) .<_ X ) -> P .< X ) ) | 
						
							| 33 | 29 22 31 15 32 | syl13anc |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> ( ( P .< ( P ( join ` K ) Q ) /\ ( P ( join ` K ) Q ) .<_ X ) -> P .< X ) ) | 
						
							| 34 | 27 33 | mpan2d |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> ( P .< ( P ( join ` K ) Q ) -> P .< X ) ) | 
						
							| 35 | 13 34 | sylbird |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> ( P =/= Q -> P .< X ) ) | 
						
							| 36 | 7 35 | pm2.61dne |  |-  ( ( K e. HL /\ ( P e. A /\ Q e. A /\ X e. B ) /\ ( P .<_ X /\ Q .< X ) ) -> P .< X ) |