| Step | Hyp | Ref | Expression | 
						
							| 1 |  | oduclatb.d |  |-  D = ( ODual ` O ) | 
						
							| 2 |  | elex |  |-  ( O e. CLat -> O e. _V ) | 
						
							| 3 |  | noel |  |-  -. ( ( lub ` (/) ) ` (/) ) e. (/) | 
						
							| 4 |  | ssid |  |-  (/) C_ (/) | 
						
							| 5 |  | base0 |  |-  (/) = ( Base ` (/) ) | 
						
							| 6 |  | eqid |  |-  ( lub ` (/) ) = ( lub ` (/) ) | 
						
							| 7 | 5 6 | clatlubcl |  |-  ( ( (/) e. CLat /\ (/) C_ (/) ) -> ( ( lub ` (/) ) ` (/) ) e. (/) ) | 
						
							| 8 | 4 7 | mpan2 |  |-  ( (/) e. CLat -> ( ( lub ` (/) ) ` (/) ) e. (/) ) | 
						
							| 9 | 3 8 | mto |  |-  -. (/) e. CLat | 
						
							| 10 |  | fvprc |  |-  ( -. O e. _V -> ( ODual ` O ) = (/) ) | 
						
							| 11 | 1 10 | eqtrid |  |-  ( -. O e. _V -> D = (/) ) | 
						
							| 12 | 11 | eleq1d |  |-  ( -. O e. _V -> ( D e. CLat <-> (/) e. CLat ) ) | 
						
							| 13 | 9 12 | mtbiri |  |-  ( -. O e. _V -> -. D e. CLat ) | 
						
							| 14 | 13 | con4i |  |-  ( D e. CLat -> O e. _V ) | 
						
							| 15 | 1 | oduposb |  |-  ( O e. _V -> ( O e. Poset <-> D e. Poset ) ) | 
						
							| 16 |  | ancom |  |-  ( ( dom ( lub ` O ) = ~P ( Base ` O ) /\ dom ( glb ` O ) = ~P ( Base ` O ) ) <-> ( dom ( glb ` O ) = ~P ( Base ` O ) /\ dom ( lub ` O ) = ~P ( Base ` O ) ) ) | 
						
							| 17 |  | eqid |  |-  ( glb ` O ) = ( glb ` O ) | 
						
							| 18 | 1 17 | odulub |  |-  ( O e. _V -> ( glb ` O ) = ( lub ` D ) ) | 
						
							| 19 | 18 | dmeqd |  |-  ( O e. _V -> dom ( glb ` O ) = dom ( lub ` D ) ) | 
						
							| 20 | 19 | eqeq1d |  |-  ( O e. _V -> ( dom ( glb ` O ) = ~P ( Base ` O ) <-> dom ( lub ` D ) = ~P ( Base ` O ) ) ) | 
						
							| 21 |  | eqid |  |-  ( lub ` O ) = ( lub ` O ) | 
						
							| 22 | 1 21 | oduglb |  |-  ( O e. _V -> ( lub ` O ) = ( glb ` D ) ) | 
						
							| 23 | 22 | dmeqd |  |-  ( O e. _V -> dom ( lub ` O ) = dom ( glb ` D ) ) | 
						
							| 24 | 23 | eqeq1d |  |-  ( O e. _V -> ( dom ( lub ` O ) = ~P ( Base ` O ) <-> dom ( glb ` D ) = ~P ( Base ` O ) ) ) | 
						
							| 25 | 20 24 | anbi12d |  |-  ( O e. _V -> ( ( dom ( glb ` O ) = ~P ( Base ` O ) /\ dom ( lub ` O ) = ~P ( Base ` O ) ) <-> ( dom ( lub ` D ) = ~P ( Base ` O ) /\ dom ( glb ` D ) = ~P ( Base ` O ) ) ) ) | 
						
							| 26 | 16 25 | bitrid |  |-  ( O e. _V -> ( ( dom ( lub ` O ) = ~P ( Base ` O ) /\ dom ( glb ` O ) = ~P ( Base ` O ) ) <-> ( dom ( lub ` D ) = ~P ( Base ` O ) /\ dom ( glb ` D ) = ~P ( Base ` O ) ) ) ) | 
						
							| 27 | 15 26 | anbi12d |  |-  ( O e. _V -> ( ( O e. Poset /\ ( dom ( lub ` O ) = ~P ( Base ` O ) /\ dom ( glb ` O ) = ~P ( Base ` O ) ) ) <-> ( D e. Poset /\ ( dom ( lub ` D ) = ~P ( Base ` O ) /\ dom ( glb ` D ) = ~P ( Base ` O ) ) ) ) ) | 
						
							| 28 |  | eqid |  |-  ( Base ` O ) = ( Base ` O ) | 
						
							| 29 | 28 21 17 | isclat |  |-  ( O e. CLat <-> ( O e. Poset /\ ( dom ( lub ` O ) = ~P ( Base ` O ) /\ dom ( glb ` O ) = ~P ( Base ` O ) ) ) ) | 
						
							| 30 | 1 28 | odubas |  |-  ( Base ` O ) = ( Base ` D ) | 
						
							| 31 |  | eqid |  |-  ( lub ` D ) = ( lub ` D ) | 
						
							| 32 |  | eqid |  |-  ( glb ` D ) = ( glb ` D ) | 
						
							| 33 | 30 31 32 | isclat |  |-  ( D e. CLat <-> ( D e. Poset /\ ( dom ( lub ` D ) = ~P ( Base ` O ) /\ dom ( glb ` D ) = ~P ( Base ` O ) ) ) ) | 
						
							| 34 | 27 29 33 | 3bitr4g |  |-  ( O e. _V -> ( O e. CLat <-> D e. CLat ) ) | 
						
							| 35 | 2 14 34 | pm5.21nii |  |-  ( O e. CLat <-> D e. CLat ) |