| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							osumcllem.l | 
							⊢  ≤   =  ( le ‘ 𝐾 )  | 
						
						
							| 2 | 
							
								
							 | 
							osumcllem.j | 
							⊢  ∨   =  ( join ‘ 𝐾 )  | 
						
						
							| 3 | 
							
								
							 | 
							osumcllem.a | 
							⊢ 𝐴  =  ( Atoms ‘ 𝐾 )  | 
						
						
							| 4 | 
							
								
							 | 
							osumcllem.p | 
							⊢  +   =  ( +𝑃 ‘ 𝐾 )  | 
						
						
							| 5 | 
							
								
							 | 
							osumcllem.o | 
							⊢  ⊥   =  ( ⊥𝑃 ‘ 𝐾 )  | 
						
						
							| 6 | 
							
								
							 | 
							osumcllem.c | 
							⊢ 𝐶  =  ( PSubCl ‘ 𝐾 )  | 
						
						
							| 7 | 
							
								
							 | 
							osumcllem.m | 
							⊢ 𝑀  =  ( 𝑋  +  { 𝑝 } )  | 
						
						
							| 8 | 
							
								
							 | 
							osumcllem.u | 
							⊢ 𝑈  =  (  ⊥  ‘ (  ⊥  ‘ ( 𝑋  +  𝑌 ) ) )  | 
						
						
							| 9 | 
							
								
							 | 
							incom | 
							⊢ ( (  ⊥  ‘ 𝑋 )  ∩  𝑈 )  =  ( 𝑈  ∩  (  ⊥  ‘ 𝑋 ) )  | 
						
						
							| 10 | 
							
								
							 | 
							simp1 | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  𝐾  ∈  HL )  | 
						
						
							| 11 | 
							
								
							 | 
							simp3 | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  | 
						
						
							| 12 | 
							
								3 6
							 | 
							psubclssatN | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶 )  →  𝑌  ⊆  𝐴 )  | 
						
						
							| 13 | 
							
								12
							 | 
							3adant3 | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  𝑌  ⊆  𝐴 )  | 
						
						
							| 14 | 
							
								3 5
							 | 
							polssatN | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴 )  →  (  ⊥  ‘ 𝑌 )  ⊆  𝐴 )  | 
						
						
							| 15 | 
							
								10 13 14
							 | 
							syl2anc | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  (  ⊥  ‘ 𝑌 )  ⊆  𝐴 )  | 
						
						
							| 16 | 
							
								11 15
							 | 
							sstrd | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  𝑋  ⊆  𝐴 )  | 
						
						
							| 17 | 
							
								3 4 5
							 | 
							poldmj1N | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  →  (  ⊥  ‘ ( 𝑋  +  𝑌 ) )  =  ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑌 ) ) )  | 
						
						
							| 18 | 
							
								10 16 13 17
							 | 
							syl3anc | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  (  ⊥  ‘ ( 𝑋  +  𝑌 ) )  =  ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑌 ) ) )  | 
						
						
							| 19 | 
							
								
							 | 
							incom | 
							⊢ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ 𝑌 ) )  =  ( (  ⊥  ‘ 𝑌 )  ∩  (  ⊥  ‘ 𝑋 ) )  | 
						
						
							| 20 | 
							
								18 19
							 | 
							eqtrdi | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  (  ⊥  ‘ ( 𝑋  +  𝑌 ) )  =  ( (  ⊥  ‘ 𝑌 )  ∩  (  ⊥  ‘ 𝑋 ) ) )  | 
						
						
							| 21 | 
							
								20
							 | 
							fveq2d | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  (  ⊥  ‘ (  ⊥  ‘ ( 𝑋  +  𝑌 ) ) )  =  (  ⊥  ‘ ( (  ⊥  ‘ 𝑌 )  ∩  (  ⊥  ‘ 𝑋 ) ) ) )  | 
						
						
							| 22 | 
							
								8 21
							 | 
							eqtrid | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  𝑈  =  (  ⊥  ‘ ( (  ⊥  ‘ 𝑌 )  ∩  (  ⊥  ‘ 𝑋 ) ) ) )  | 
						
						
							| 23 | 
							
								22
							 | 
							ineq1d | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  ( 𝑈  ∩  (  ⊥  ‘ 𝑋 ) )  =  ( (  ⊥  ‘ ( (  ⊥  ‘ 𝑌 )  ∩  (  ⊥  ‘ 𝑋 ) ) )  ∩  (  ⊥  ‘ 𝑋 ) ) )  | 
						
						
							| 24 | 
							
								3 5
							 | 
							polcon2N | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  𝑌  ⊆  (  ⊥  ‘ 𝑋 ) )  | 
						
						
							| 25 | 
							
								13 24
							 | 
							syld3an2 | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  𝑌  ⊆  (  ⊥  ‘ 𝑋 ) )  | 
						
						
							| 26 | 
							
								3 5
							 | 
							poml5N | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  (  ⊥  ‘ 𝑋 ) )  →  ( (  ⊥  ‘ ( (  ⊥  ‘ 𝑌 )  ∩  (  ⊥  ‘ 𝑋 ) ) )  ∩  (  ⊥  ‘ 𝑋 ) )  =  (  ⊥  ‘ (  ⊥  ‘ 𝑌 ) ) )  | 
						
						
							| 27 | 
							
								10 16 25 26
							 | 
							syl3anc | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  ( (  ⊥  ‘ ( (  ⊥  ‘ 𝑌 )  ∩  (  ⊥  ‘ 𝑋 ) ) )  ∩  (  ⊥  ‘ 𝑋 ) )  =  (  ⊥  ‘ (  ⊥  ‘ 𝑌 ) ) )  | 
						
						
							| 28 | 
							
								5 6
							 | 
							psubcli2N | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶 )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑌 ) )  =  𝑌 )  | 
						
						
							| 29 | 
							
								28
							 | 
							3adant3 | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑌 ) )  =  𝑌 )  | 
						
						
							| 30 | 
							
								23 27 29
							 | 
							3eqtrd | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  ( 𝑈  ∩  (  ⊥  ‘ 𝑋 ) )  =  𝑌 )  | 
						
						
							| 31 | 
							
								9 30
							 | 
							eqtrid | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ∈  𝐶  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  ( (  ⊥  ‘ 𝑋 )  ∩  𝑈 )  =  𝑌 )  |