| Step | Hyp | Ref | Expression | 
						
							| 1 |  | atexchlt.s | ⊢  <   =  ( lt ‘ 𝐾 ) | 
						
							| 2 |  | atexchlt.j | ⊢  ∨   =  ( join ‘ 𝐾 ) | 
						
							| 3 |  | atexchlt.a | ⊢ 𝐴  =  ( Atoms ‘ 𝐾 ) | 
						
							| 4 |  | eqid | ⊢ (  ⋖  ‘ 𝐾 )  =  (  ⋖  ‘ 𝐾 ) | 
						
							| 5 | 2 3 4 | atexchcvrN | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑃  ∈  𝐴  ∧  𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴 )  ∧  𝑃  ≠  𝑅 )  →  ( 𝑃 (  ⋖  ‘ 𝐾 ) ( 𝑄  ∨  𝑅 )  →  𝑄 (  ⋖  ‘ 𝐾 ) ( 𝑃  ∨  𝑅 ) ) ) | 
						
							| 6 | 1 2 3 4 | atltcvr | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑃  ∈  𝐴  ∧  𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴 ) )  →  ( 𝑃  <  ( 𝑄  ∨  𝑅 )  ↔  𝑃 (  ⋖  ‘ 𝐾 ) ( 𝑄  ∨  𝑅 ) ) ) | 
						
							| 7 | 6 | 3adant3 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑃  ∈  𝐴  ∧  𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴 )  ∧  𝑃  ≠  𝑅 )  →  ( 𝑃  <  ( 𝑄  ∨  𝑅 )  ↔  𝑃 (  ⋖  ‘ 𝐾 ) ( 𝑄  ∨  𝑅 ) ) ) | 
						
							| 8 |  | simpl | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑃  ∈  𝐴  ∧  𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴 ) )  →  𝐾  ∈  HL ) | 
						
							| 9 |  | simpr2 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑃  ∈  𝐴  ∧  𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴 ) )  →  𝑄  ∈  𝐴 ) | 
						
							| 10 |  | simpr1 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑃  ∈  𝐴  ∧  𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴 ) )  →  𝑃  ∈  𝐴 ) | 
						
							| 11 |  | simpr3 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑃  ∈  𝐴  ∧  𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴 ) )  →  𝑅  ∈  𝐴 ) | 
						
							| 12 | 1 2 3 4 | atltcvr | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑄  ∈  𝐴  ∧  𝑃  ∈  𝐴  ∧  𝑅  ∈  𝐴 ) )  →  ( 𝑄  <  ( 𝑃  ∨  𝑅 )  ↔  𝑄 (  ⋖  ‘ 𝐾 ) ( 𝑃  ∨  𝑅 ) ) ) | 
						
							| 13 | 8 9 10 11 12 | syl13anc | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑃  ∈  𝐴  ∧  𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴 ) )  →  ( 𝑄  <  ( 𝑃  ∨  𝑅 )  ↔  𝑄 (  ⋖  ‘ 𝐾 ) ( 𝑃  ∨  𝑅 ) ) ) | 
						
							| 14 | 13 | 3adant3 | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑃  ∈  𝐴  ∧  𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴 )  ∧  𝑃  ≠  𝑅 )  →  ( 𝑄  <  ( 𝑃  ∨  𝑅 )  ↔  𝑄 (  ⋖  ‘ 𝐾 ) ( 𝑃  ∨  𝑅 ) ) ) | 
						
							| 15 | 5 7 14 | 3imtr4d | ⊢ ( ( 𝐾  ∈  HL  ∧  ( 𝑃  ∈  𝐴  ∧  𝑄  ∈  𝐴  ∧  𝑅  ∈  𝐴 )  ∧  𝑃  ≠  𝑅 )  →  ( 𝑃  <  ( 𝑄  ∨  𝑅 )  →  𝑄  <  ( 𝑃  ∨  𝑅 ) ) ) |