| 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 |  | n0i | ⊢ ( 𝑟  ∈  ( 𝑋  ∩  𝑌 )  →  ¬  ( 𝑋  ∩  𝑌 )  =  ∅ ) | 
						
							| 10 |  | incom | ⊢ ( 𝑋  ∩  𝑌 )  =  ( 𝑌  ∩  𝑋 ) | 
						
							| 11 |  | sslin | ⊢ ( 𝑋  ⊆  (  ⊥  ‘ 𝑌 )  →  ( 𝑌  ∩  𝑋 )  ⊆  ( 𝑌  ∩  (  ⊥  ‘ 𝑌 ) ) ) | 
						
							| 12 | 11 | 3ad2ant3 | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  ( 𝑌  ∩  𝑋 )  ⊆  ( 𝑌  ∩  (  ⊥  ‘ 𝑌 ) ) ) | 
						
							| 13 | 10 12 | eqsstrid | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  ( 𝑋  ∩  𝑌 )  ⊆  ( 𝑌  ∩  (  ⊥  ‘ 𝑌 ) ) ) | 
						
							| 14 | 3 5 | pnonsingN | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴 )  →  ( 𝑌  ∩  (  ⊥  ‘ 𝑌 ) )  =  ∅ ) | 
						
							| 15 | 14 | 3adant3 | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  ( 𝑌  ∩  (  ⊥  ‘ 𝑌 ) )  =  ∅ ) | 
						
							| 16 | 13 15 | sseqtrd | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  ( 𝑋  ∩  𝑌 )  ⊆  ∅ ) | 
						
							| 17 |  | ss0b | ⊢ ( ( 𝑋  ∩  𝑌 )  ⊆  ∅  ↔  ( 𝑋  ∩  𝑌 )  =  ∅ ) | 
						
							| 18 | 16 17 | sylib | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  →  ( 𝑋  ∩  𝑌 )  =  ∅ ) | 
						
							| 19 | 18 | adantr | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  ∧  ( 𝑟  ∈  𝑋  ∧  𝑞  ∈  𝑌 ) )  →  ( 𝑋  ∩  𝑌 )  =  ∅ ) | 
						
							| 20 | 9 19 | nsyl3 | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  ∧  ( 𝑟  ∈  𝑋  ∧  𝑞  ∈  𝑌 ) )  →  ¬  𝑟  ∈  ( 𝑋  ∩  𝑌 ) ) | 
						
							| 21 |  | simprr | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  ∧  ( 𝑟  ∈  𝑋  ∧  𝑞  ∈  𝑌 ) )  →  𝑞  ∈  𝑌 ) | 
						
							| 22 |  | eleq1w | ⊢ ( 𝑞  =  𝑟  →  ( 𝑞  ∈  𝑌  ↔  𝑟  ∈  𝑌 ) ) | 
						
							| 23 | 21 22 | syl5ibcom | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  ∧  ( 𝑟  ∈  𝑋  ∧  𝑞  ∈  𝑌 ) )  →  ( 𝑞  =  𝑟  →  𝑟  ∈  𝑌 ) ) | 
						
							| 24 |  | simprl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  ∧  ( 𝑟  ∈  𝑋  ∧  𝑞  ∈  𝑌 ) )  →  𝑟  ∈  𝑋 ) | 
						
							| 25 | 23 24 | jctild | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  ∧  ( 𝑟  ∈  𝑋  ∧  𝑞  ∈  𝑌 ) )  →  ( 𝑞  =  𝑟  →  ( 𝑟  ∈  𝑋  ∧  𝑟  ∈  𝑌 ) ) ) | 
						
							| 26 |  | elin | ⊢ ( 𝑟  ∈  ( 𝑋  ∩  𝑌 )  ↔  ( 𝑟  ∈  𝑋  ∧  𝑟  ∈  𝑌 ) ) | 
						
							| 27 | 25 26 | imbitrrdi | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  ∧  ( 𝑟  ∈  𝑋  ∧  𝑞  ∈  𝑌 ) )  →  ( 𝑞  =  𝑟  →  𝑟  ∈  ( 𝑋  ∩  𝑌 ) ) ) | 
						
							| 28 | 27 | necon3bd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  ∧  ( 𝑟  ∈  𝑋  ∧  𝑞  ∈  𝑌 ) )  →  ( ¬  𝑟  ∈  ( 𝑋  ∩  𝑌 )  →  𝑞  ≠  𝑟 ) ) | 
						
							| 29 | 20 28 | mpd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑌  ⊆  𝐴  ∧  𝑋  ⊆  (  ⊥  ‘ 𝑌 ) )  ∧  ( 𝑟  ∈  𝑋  ∧  𝑞  ∈  𝑌 ) )  →  𝑞  ≠  𝑟 ) |