| 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 ) |