| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							4thatlem.ph | 
							⊢ ( 𝜑  ↔  ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑃  ∈  𝐴  ∧  ¬  𝑃  ≤  𝑊 )  ∧  ( 𝑄  ∈  𝐴  ∧  ¬  𝑄  ≤  𝑊 ) )  ∧  ( 𝑆  ∈  𝐴  ∧  ( 𝑅  ∈  𝐴  ∧  ¬  𝑅  ≤  𝑊  ∧  ( 𝑃  ∨  𝑅 )  =  ( 𝑄  ∨  𝑅 ) )  ∧  ( 𝑇  ∈  𝐴  ∧  ( 𝑈  ∨  𝑇 )  =  ( 𝑉  ∨  𝑇 ) ) )  ∧  ( 𝑃  ≠  𝑄  ∧  ¬  𝑆  ≤  ( 𝑃  ∨  𝑄 ) ) ) )  | 
						
						
							| 2 | 
							
								
							 | 
							4thatlem0.l | 
							⊢  ≤   =  ( le ‘ 𝐾 )  | 
						
						
							| 3 | 
							
								
							 | 
							4thatlem0.j | 
							⊢  ∨   =  ( join ‘ 𝐾 )  | 
						
						
							| 4 | 
							
								
							 | 
							4thatlem0.m | 
							⊢  ∧   =  ( meet ‘ 𝐾 )  | 
						
						
							| 5 | 
							
								
							 | 
							4thatlem0.a | 
							⊢ 𝐴  =  ( Atoms ‘ 𝐾 )  | 
						
						
							| 6 | 
							
								
							 | 
							4thatlem0.h | 
							⊢ 𝐻  =  ( LHyp ‘ 𝐾 )  | 
						
						
							| 7 | 
							
								
							 | 
							4thatlem0.u | 
							⊢ 𝑈  =  ( ( 𝑃  ∨  𝑄 )  ∧  𝑊 )  | 
						
						
							| 8 | 
							
								
							 | 
							4thatlem0.v | 
							⊢ 𝑉  =  ( ( 𝑃  ∨  𝑆 )  ∧  𝑊 )  | 
						
						
							| 9 | 
							
								1
							 | 
							4atexlemk | 
							⊢ ( 𝜑  →  𝐾  ∈  HL )  | 
						
						
							| 10 | 
							
								1
							 | 
							4atexlemw | 
							⊢ ( 𝜑  →  𝑊  ∈  𝐻 )  | 
						
						
							| 11 | 
							
								1
							 | 
							4atexlempw | 
							⊢ ( 𝜑  →  ( 𝑃  ∈  𝐴  ∧  ¬  𝑃  ≤  𝑊 ) )  | 
						
						
							| 12 | 
							
								1
							 | 
							4atexlems | 
							⊢ ( 𝜑  →  𝑆  ∈  𝐴 )  | 
						
						
							| 13 | 
							
								1 2 3 5
							 | 
							4atexlempns | 
							⊢ ( 𝜑  →  𝑃  ≠  𝑆 )  | 
						
						
							| 14 | 
							
								2 3 4 5 6 8
							 | 
							lhpat2 | 
							⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑃  ∈  𝐴  ∧  ¬  𝑃  ≤  𝑊 )  ∧  ( 𝑆  ∈  𝐴  ∧  𝑃  ≠  𝑆 ) )  →  𝑉  ∈  𝐴 )  | 
						
						
							| 15 | 
							
								9 10 11 12 13 14
							 | 
							syl212anc | 
							⊢ ( 𝜑  →  𝑉  ∈  𝐴 )  |