| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							poml6.c | 
							⊢ 𝐶  =  ( PSubCl ‘ 𝐾 )  | 
						
						
							| 2 | 
							
								
							 | 
							poml6.p | 
							⊢  ⊥   =  ( ⊥𝑃 ‘ 𝐾 )  | 
						
						
							| 3 | 
							
								
							 | 
							simpl1 | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶  ∧  𝑌  ∈  𝐶 )  ∧  𝑋  ⊆  𝑌 )  →  𝐾  ∈  HL )  | 
						
						
							| 4 | 
							
								
							 | 
							simpl2 | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶  ∧  𝑌  ∈  𝐶 )  ∧  𝑋  ⊆  𝑌 )  →  𝑋  ∈  𝐶 )  | 
						
						
							| 5 | 
							
								
							 | 
							eqid | 
							⊢ ( Atoms ‘ 𝐾 )  =  ( Atoms ‘ 𝐾 )  | 
						
						
							| 6 | 
							
								5 1
							 | 
							psubclssatN | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶 )  →  𝑋  ⊆  ( Atoms ‘ 𝐾 ) )  | 
						
						
							| 7 | 
							
								3 4 6
							 | 
							syl2anc | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶  ∧  𝑌  ∈  𝐶 )  ∧  𝑋  ⊆  𝑌 )  →  𝑋  ⊆  ( Atoms ‘ 𝐾 ) )  | 
						
						
							| 8 | 
							
								
							 | 
							simpl3 | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶  ∧  𝑌  ∈  𝐶 )  ∧  𝑋  ⊆  𝑌 )  →  𝑌  ∈  𝐶 )  | 
						
						
							| 9 | 
							
								5 1
							 | 
							psubclssatN | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶 )  →  𝑌  ⊆  ( Atoms ‘ 𝐾 ) )  | 
						
						
							| 10 | 
							
								3 8 9
							 | 
							syl2anc | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶  ∧  𝑌  ∈  𝐶 )  ∧  𝑋  ⊆  𝑌 )  →  𝑌  ⊆  ( Atoms ‘ 𝐾 ) )  | 
						
						
							| 11 | 
							
								
							 | 
							simpr | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶  ∧  𝑌  ∈  𝐶 )  ∧  𝑋  ⊆  𝑌 )  →  𝑋  ⊆  𝑌 )  | 
						
						
							| 12 | 
							
								2 1
							 | 
							psubcli2N | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶 )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑌 ) )  =  𝑌 )  | 
						
						
							| 13 | 
							
								3 8 12
							 | 
							syl2anc | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶  ∧  𝑌  ∈  𝐶 )  ∧  𝑋  ⊆  𝑌 )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑌 ) )  =  𝑌 )  | 
						
						
							| 14 | 
							
								5 2
							 | 
							poml4N | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  ( Atoms ‘ 𝐾 )  ∧  𝑌  ⊆  ( Atoms ‘ 𝐾 ) )  →  ( ( 𝑋  ⊆  𝑌  ∧  (  ⊥  ‘ (  ⊥  ‘ 𝑌 ) )  =  𝑌 )  →  ( (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  𝑌 ) )  ∩  𝑌 )  =  (  ⊥  ‘ (  ⊥  ‘ 𝑋 ) ) ) )  | 
						
						
							| 15 | 
							
								14
							 | 
							imp | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  ( Atoms ‘ 𝐾 )  ∧  𝑌  ⊆  ( Atoms ‘ 𝐾 ) )  ∧  ( 𝑋  ⊆  𝑌  ∧  (  ⊥  ‘ (  ⊥  ‘ 𝑌 ) )  =  𝑌 ) )  →  ( (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  𝑌 ) )  ∩  𝑌 )  =  (  ⊥  ‘ (  ⊥  ‘ 𝑋 ) ) )  | 
						
						
							| 16 | 
							
								3 7 10 11 13 15
							 | 
							syl32anc | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶  ∧  𝑌  ∈  𝐶 )  ∧  𝑋  ⊆  𝑌 )  →  ( (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  𝑌 ) )  ∩  𝑌 )  =  (  ⊥  ‘ (  ⊥  ‘ 𝑋 ) ) )  | 
						
						
							| 17 | 
							
								2 1
							 | 
							psubcli2N | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶 )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑋 ) )  =  𝑋 )  | 
						
						
							| 18 | 
							
								3 4 17
							 | 
							syl2anc | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶  ∧  𝑌  ∈  𝐶 )  ∧  𝑋  ⊆  𝑌 )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑋 ) )  =  𝑋 )  | 
						
						
							| 19 | 
							
								16 18
							 | 
							eqtrd | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ∈  𝐶  ∧  𝑌  ∈  𝐶 )  ∧  𝑋  ⊆  𝑌 )  →  ( (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  𝑌 ) )  ∩  𝑌 )  =  𝑋 )  |