| Step | Hyp | Ref | Expression | 
						
							| 1 |  | lplni2.l | ⊢  ≤   =  ( le ‘ 𝐾 ) | 
						
							| 2 |  | lplni2.j | ⊢  ∨   =  ( join ‘ 𝐾 ) | 
						
							| 3 |  | lplni2.a | ⊢ 𝐴  =  ( Atoms ‘ 𝐾 ) | 
						
							| 4 |  | lplni2.p | ⊢ 𝑃  =  ( LPlanes ‘ 𝐾 ) | 
						
							| 5 |  | simp2 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 ) ) | 
						
							| 6 |  | simp3l | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  𝑄  ≠  𝑅 ) | 
						
							| 7 |  | simp3r | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) | 
						
							| 8 |  | eqidd | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 ) ) | 
						
							| 9 |  | neeq1 | ⊢ ( 𝑞  =  𝑄  →  ( 𝑞  ≠  𝑟  ↔  𝑄  ≠  𝑟 ) ) | 
						
							| 10 |  | oveq1 | ⊢ ( 𝑞  =  𝑄  →  ( 𝑞  ∨  𝑟 )  =  ( 𝑄  ∨  𝑟 ) ) | 
						
							| 11 | 10 | breq2d | ⊢ ( 𝑞  =  𝑄  →  ( 𝑠  ≤  ( 𝑞  ∨  𝑟 )  ↔  𝑠  ≤  ( 𝑄  ∨  𝑟 ) ) ) | 
						
							| 12 | 11 | notbid | ⊢ ( 𝑞  =  𝑄  →  ( ¬  𝑠  ≤  ( 𝑞  ∨  𝑟 )  ↔  ¬  𝑠  ≤  ( 𝑄  ∨  𝑟 ) ) ) | 
						
							| 13 | 10 | oveq1d | ⊢ ( 𝑞  =  𝑄  →  ( ( 𝑞  ∨  𝑟 )  ∨  𝑠 )  =  ( ( 𝑄  ∨  𝑟 )  ∨  𝑠 ) ) | 
						
							| 14 | 13 | eqeq2d | ⊢ ( 𝑞  =  𝑄  →  ( ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑞  ∨  𝑟 )  ∨  𝑠 )  ↔  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑟 )  ∨  𝑠 ) ) ) | 
						
							| 15 | 9 12 14 | 3anbi123d | ⊢ ( 𝑞  =  𝑄  →  ( ( 𝑞  ≠  𝑟  ∧  ¬  𝑠  ≤  ( 𝑞  ∨  𝑟 )  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑞  ∨  𝑟 )  ∨  𝑠 ) )  ↔  ( 𝑄  ≠  𝑟  ∧  ¬  𝑠  ≤  ( 𝑄  ∨  𝑟 )  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑟 )  ∨  𝑠 ) ) ) ) | 
						
							| 16 |  | neeq2 | ⊢ ( 𝑟  =  𝑅  →  ( 𝑄  ≠  𝑟  ↔  𝑄  ≠  𝑅 ) ) | 
						
							| 17 |  | oveq2 | ⊢ ( 𝑟  =  𝑅  →  ( 𝑄  ∨  𝑟 )  =  ( 𝑄  ∨  𝑅 ) ) | 
						
							| 18 | 17 | breq2d | ⊢ ( 𝑟  =  𝑅  →  ( 𝑠  ≤  ( 𝑄  ∨  𝑟 )  ↔  𝑠  ≤  ( 𝑄  ∨  𝑅 ) ) ) | 
						
							| 19 | 18 | notbid | ⊢ ( 𝑟  =  𝑅  →  ( ¬  𝑠  ≤  ( 𝑄  ∨  𝑟 )  ↔  ¬  𝑠  ≤  ( 𝑄  ∨  𝑅 ) ) ) | 
						
							| 20 | 17 | oveq1d | ⊢ ( 𝑟  =  𝑅  →  ( ( 𝑄  ∨  𝑟 )  ∨  𝑠 )  =  ( ( 𝑄  ∨  𝑅 )  ∨  𝑠 ) ) | 
						
							| 21 | 20 | eqeq2d | ⊢ ( 𝑟  =  𝑅  →  ( ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑟 )  ∨  𝑠 )  ↔  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑅 )  ∨  𝑠 ) ) ) | 
						
							| 22 | 16 19 21 | 3anbi123d | ⊢ ( 𝑟  =  𝑅  →  ( ( 𝑄  ≠  𝑟  ∧  ¬  𝑠  ≤  ( 𝑄  ∨  𝑟 )  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑟 )  ∨  𝑠 ) )  ↔  ( 𝑄  ≠  𝑅  ∧  ¬  𝑠  ≤  ( 𝑄  ∨  𝑅 )  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑅 )  ∨  𝑠 ) ) ) ) | 
						
							| 23 |  | breq1 | ⊢ ( 𝑠  =  𝑆  →  ( 𝑠  ≤  ( 𝑄  ∨  𝑅 )  ↔  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) ) | 
						
							| 24 | 23 | notbid | ⊢ ( 𝑠  =  𝑆  →  ( ¬  𝑠  ≤  ( 𝑄  ∨  𝑅 )  ↔  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) ) | 
						
							| 25 |  | oveq2 | ⊢ ( 𝑠  =  𝑆  →  ( ( 𝑄  ∨  𝑅 )  ∨  𝑠 )  =  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 ) ) | 
						
							| 26 | 25 | eqeq2d | ⊢ ( 𝑠  =  𝑆  →  ( ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑅 )  ∨  𝑠 )  ↔  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 ) ) ) | 
						
							| 27 | 24 26 | 3anbi23d | ⊢ ( 𝑠  =  𝑆  →  ( ( 𝑄  ≠  𝑅  ∧  ¬  𝑠  ≤  ( 𝑄  ∨  𝑅 )  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑅 )  ∨  𝑠 ) )  ↔  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 )  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 ) ) ) ) | 
						
							| 28 | 15 22 27 | rspc3ev | ⊢ ( ( ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 )  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 ) ) )  →  ∃ 𝑞  ∈  𝐴 ∃ 𝑟  ∈  𝐴 ∃ 𝑠  ∈  𝐴 ( 𝑞  ≠  𝑟  ∧  ¬  𝑠  ≤  ( 𝑞  ∨  𝑟 )  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑞  ∨  𝑟 )  ∨  𝑠 ) ) ) | 
						
							| 29 | 5 6 7 8 28 | syl13anc | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  ∃ 𝑞  ∈  𝐴 ∃ 𝑟  ∈  𝐴 ∃ 𝑠  ∈  𝐴 ( 𝑞  ≠  𝑟  ∧  ¬  𝑠  ≤  ( 𝑞  ∨  𝑟 )  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑞  ∨  𝑟 )  ∨  𝑠 ) ) ) | 
						
							| 30 |  | simp1 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  𝐾  ∈  HL ) | 
						
							| 31 |  | hllat | ⊢ ( 𝐾  ∈  HL  →  𝐾  ∈  Lat ) | 
						
							| 32 | 31 | 3ad2ant1 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  𝐾  ∈  Lat ) | 
						
							| 33 |  | simp21 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  𝑄  ∈  𝐴 ) | 
						
							| 34 |  | simp22 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  𝑅  ∈  𝐴 ) | 
						
							| 35 |  | eqid | ⊢ ( Base ‘ 𝐾 )  =  ( Base ‘ 𝐾 ) | 
						
							| 36 | 35 2 3 | hlatjcl | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴 )  →  ( 𝑄  ∨  𝑅 )  ∈  ( Base ‘ 𝐾 ) ) | 
						
							| 37 | 30 33 34 36 | syl3anc | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  ( 𝑄  ∨  𝑅 )  ∈  ( Base ‘ 𝐾 ) ) | 
						
							| 38 |  | simp23 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  𝑆  ∈  𝐴 ) | 
						
							| 39 | 35 3 | atbase | ⊢ ( 𝑆  ∈  𝐴  →  𝑆  ∈  ( Base ‘ 𝐾 ) ) | 
						
							| 40 | 38 39 | syl | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  𝑆  ∈  ( Base ‘ 𝐾 ) ) | 
						
							| 41 | 35 2 | latjcl | ⊢ ( ( 𝐾  ∈  Lat  ∧  ( 𝑄  ∨  𝑅 )  ∈  ( Base ‘ 𝐾 )  ∧  𝑆  ∈  ( Base ‘ 𝐾 ) )  →  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  ∈  ( Base ‘ 𝐾 ) ) | 
						
							| 42 | 32 37 40 41 | syl3anc | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  ∈  ( Base ‘ 𝐾 ) ) | 
						
							| 43 | 35 1 2 3 4 | islpln5 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  ∈  ( Base ‘ 𝐾 ) )  →  ( ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  ∈  𝑃  ↔  ∃ 𝑞  ∈  𝐴 ∃ 𝑟  ∈  𝐴 ∃ 𝑠  ∈  𝐴 ( 𝑞  ≠  𝑟  ∧  ¬  𝑠  ≤  ( 𝑞  ∨  𝑟 )  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑞  ∨  𝑟 )  ∨  𝑠 ) ) ) ) | 
						
							| 44 | 30 42 43 | syl2anc | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  ( ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  ∈  𝑃  ↔  ∃ 𝑞  ∈  𝐴 ∃ 𝑟  ∈  𝐴 ∃ 𝑠  ∈  𝐴 ( 𝑞  ≠  𝑟  ∧  ¬  𝑠  ≤  ( 𝑞  ∨  𝑟 )  ∧  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  =  ( ( 𝑞  ∨  𝑟 )  ∨  𝑠 ) ) ) ) | 
						
							| 45 | 29 44 | mpbird | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴  ∧  𝑆  ∈  𝐴 )  ∧  ( 𝑄  ≠  𝑅  ∧  ¬  𝑆  ≤  ( 𝑄  ∨  𝑅 ) ) )  →  ( ( 𝑄  ∨  𝑅 )  ∨  𝑆 )  ∈  𝑃 ) |