| 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 | 
							
								
							 | 
							simpl1 | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  𝐾  ∈  HL )  | 
						
						
							| 10 | 
							
								
							 | 
							simpl2 | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  𝑋  ⊆  𝐴 )  | 
						
						
							| 11 | 
							
								
							 | 
							simpr | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  𝑝  ∈  𝑈 )  | 
						
						
							| 12 | 
							
								11
							 | 
							snssd | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  { 𝑝 }  ⊆  𝑈 )  | 
						
						
							| 13 | 
							
								3 4
							 | 
							paddssat | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  →  ( 𝑋  +  𝑌 )  ⊆  𝐴 )  | 
						
						
							| 14 | 
							
								13
							 | 
							adantr | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  ( 𝑋  +  𝑌 )  ⊆  𝐴 )  | 
						
						
							| 15 | 
							
								3 5
							 | 
							polssatN | 
							⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑋  +  𝑌 )  ⊆  𝐴 )  →  (  ⊥  ‘ ( 𝑋  +  𝑌 ) )  ⊆  𝐴 )  | 
						
						
							| 16 | 
							
								9 14 15
							 | 
							syl2anc | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  (  ⊥  ‘ ( 𝑋  +  𝑌 ) )  ⊆  𝐴 )  | 
						
						
							| 17 | 
							
								3 5
							 | 
							polssatN | 
							⊢ ( ( 𝐾  ∈  HL  ∧  (  ⊥  ‘ ( 𝑋  +  𝑌 ) )  ⊆  𝐴 )  →  (  ⊥  ‘ (  ⊥  ‘ ( 𝑋  +  𝑌 ) ) )  ⊆  𝐴 )  | 
						
						
							| 18 | 
							
								9 16 17
							 | 
							syl2anc | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  (  ⊥  ‘ (  ⊥  ‘ ( 𝑋  +  𝑌 ) ) )  ⊆  𝐴 )  | 
						
						
							| 19 | 
							
								8 18
							 | 
							eqsstrid | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  𝑈  ⊆  𝐴 )  | 
						
						
							| 20 | 
							
								12 19
							 | 
							sstrd | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  { 𝑝 }  ⊆  𝐴 )  | 
						
						
							| 21 | 
							
								3 4
							 | 
							sspadd1 | 
							⊢ ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  { 𝑝 }  ⊆  𝐴 )  →  𝑋  ⊆  ( 𝑋  +  { 𝑝 } ) )  | 
						
						
							| 22 | 
							
								9 10 20 21
							 | 
							syl3anc | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  𝑋  ⊆  ( 𝑋  +  { 𝑝 } ) )  | 
						
						
							| 23 | 
							
								22 7
							 | 
							sseqtrrdi | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  𝑋  ⊆  𝑀 )  | 
						
						
							| 24 | 
							
								1 2 3 4 5 6 7 8
							 | 
							osumcllem1N | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  ( 𝑈  ∩  𝑀 )  =  𝑀 )  | 
						
						
							| 25 | 
							
								23 24
							 | 
							sseqtrrd | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑋  ⊆  𝐴  ∧  𝑌  ⊆  𝐴 )  ∧  𝑝  ∈  𝑈 )  →  𝑋  ⊆  ( 𝑈  ∩  𝑀 ) )  |