| 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 2 3 4 5 6 7 8
							 | 
							4atexlemtlw | 
							⊢ ( 𝜑  →  𝑇  ≤  𝑊 )  | 
						
						
							| 10 | 
							
								1
							 | 
							4atexlemkc | 
							⊢ ( 𝜑  →  𝐾  ∈  CvLat )  | 
						
						
							| 11 | 
							
								1 2 3 4 5 6 7
							 | 
							4atexlemu | 
							⊢ ( 𝜑  →  𝑈  ∈  𝐴 )  | 
						
						
							| 12 | 
							
								1 2 3 4 5 6 7 8
							 | 
							4atexlemv | 
							⊢ ( 𝜑  →  𝑉  ∈  𝐴 )  | 
						
						
							| 13 | 
							
								1
							 | 
							4atexlemt | 
							⊢ ( 𝜑  →  𝑇  ∈  𝐴 )  | 
						
						
							| 14 | 
							
								1 2 3 4 5 6 7 8
							 | 
							4atexlemunv | 
							⊢ ( 𝜑  →  𝑈  ≠  𝑉 )  | 
						
						
							| 15 | 
							
								1
							 | 
							4atexlemutvt | 
							⊢ ( 𝜑  →  ( 𝑈  ∨  𝑇 )  =  ( 𝑉  ∨  𝑇 ) )  | 
						
						
							| 16 | 
							
								5 3
							 | 
							cvlsupr5 | 
							⊢ ( ( 𝐾  ∈  CvLat  ∧  ( 𝑈  ∈  𝐴  ∧  𝑉  ∈  𝐴  ∧  𝑇  ∈  𝐴 )  ∧  ( 𝑈  ≠  𝑉  ∧  ( 𝑈  ∨  𝑇 )  =  ( 𝑉  ∨  𝑇 ) ) )  →  𝑇  ≠  𝑈 )  | 
						
						
							| 17 | 
							
								10 11 12 13 14 15 16
							 | 
							syl132anc | 
							⊢ ( 𝜑  →  𝑇  ≠  𝑈 )  | 
						
						
							| 18 | 
							
								17
							 | 
							adantr | 
							⊢ ( ( 𝜑  ∧  𝑇  ≤  ( 𝑃  ∨  𝑄 ) )  →  𝑇  ≠  𝑈 )  | 
						
						
							| 19 | 
							
								1
							 | 
							4atexlemk | 
							⊢ ( 𝜑  →  𝐾  ∈  HL )  | 
						
						
							| 20 | 
							
								1
							 | 
							4atexlemw | 
							⊢ ( 𝜑  →  𝑊  ∈  𝐻 )  | 
						
						
							| 21 | 
							
								19 20
							 | 
							jca | 
							⊢ ( 𝜑  →  ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 ) )  | 
						
						
							| 22 | 
							
								21
							 | 
							adantr | 
							⊢ ( ( 𝜑  ∧  𝑇  ≤  ( 𝑃  ∨  𝑄 ) )  →  ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 ) )  | 
						
						
							| 23 | 
							
								1
							 | 
							4atexlempw | 
							⊢ ( 𝜑  →  ( 𝑃  ∈  𝐴  ∧  ¬  𝑃  ≤  𝑊 ) )  | 
						
						
							| 24 | 
							
								23
							 | 
							adantr | 
							⊢ ( ( 𝜑  ∧  𝑇  ≤  ( 𝑃  ∨  𝑄 ) )  →  ( 𝑃  ∈  𝐴  ∧  ¬  𝑃  ≤  𝑊 ) )  | 
						
						
							| 25 | 
							
								1
							 | 
							4atexlemq | 
							⊢ ( 𝜑  →  𝑄  ∈  𝐴 )  | 
						
						
							| 26 | 
							
								25
							 | 
							adantr | 
							⊢ ( ( 𝜑  ∧  𝑇  ≤  ( 𝑃  ∨  𝑄 ) )  →  𝑄  ∈  𝐴 )  | 
						
						
							| 27 | 
							
								13
							 | 
							adantr | 
							⊢ ( ( 𝜑  ∧  𝑇  ≤  ( 𝑃  ∨  𝑄 ) )  →  𝑇  ∈  𝐴 )  | 
						
						
							| 28 | 
							
								1
							 | 
							4atexlempnq | 
							⊢ ( 𝜑  →  𝑃  ≠  𝑄 )  | 
						
						
							| 29 | 
							
								28
							 | 
							adantr | 
							⊢ ( ( 𝜑  ∧  𝑇  ≤  ( 𝑃  ∨  𝑄 ) )  →  𝑃  ≠  𝑄 )  | 
						
						
							| 30 | 
							
								
							 | 
							simpr | 
							⊢ ( ( 𝜑  ∧  𝑇  ≤  ( 𝑃  ∨  𝑄 ) )  →  𝑇  ≤  ( 𝑃  ∨  𝑄 ) )  | 
						
						
							| 31 | 
							
								2 3 4 5 6 7
							 | 
							lhpat3 | 
							⊢ ( ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑃  ∈  𝐴  ∧  ¬  𝑃  ≤  𝑊 ) )  ∧  ( 𝑄  ∈  𝐴  ∧  𝑇  ∈  𝐴 )  ∧  ( 𝑃  ≠  𝑄  ∧  𝑇  ≤  ( 𝑃  ∨  𝑄 ) ) )  →  ( ¬  𝑇  ≤  𝑊  ↔  𝑇  ≠  𝑈 ) )  | 
						
						
							| 32 | 
							
								22 24 26 27 29 30 31
							 | 
							syl222anc | 
							⊢ ( ( 𝜑  ∧  𝑇  ≤  ( 𝑃  ∨  𝑄 ) )  →  ( ¬  𝑇  ≤  𝑊  ↔  𝑇  ≠  𝑈 ) )  | 
						
						
							| 33 | 
							
								18 32
							 | 
							mpbird | 
							⊢ ( ( 𝜑  ∧  𝑇  ≤  ( 𝑃  ∨  𝑄 ) )  →  ¬  𝑇  ≤  𝑊 )  | 
						
						
							| 34 | 
							
								33
							 | 
							ex | 
							⊢ ( 𝜑  →  ( 𝑇  ≤  ( 𝑃  ∨  𝑄 )  →  ¬  𝑇  ≤  𝑊 ) )  | 
						
						
							| 35 | 
							
								9 34
							 | 
							mt2d | 
							⊢ ( 𝜑  →  ¬  𝑇  ≤  ( 𝑃  ∨  𝑄 ) )  |