Metamath Proof Explorer
		
		
		
		Description:  The half-line relation is reflexive.  Theorem 6.5 of Schwabhauser
         p. 44.  (Contributed by Thierry Arnoux, 21-Feb-2020)
		
			
				
					 | 
					 | 
					Ref | 
					Expression | 
				
					
						 | 
						Hypotheses | 
						ishlg.p | 
						⊢ 𝑃  =  ( Base ‘ 𝐺 )  | 
					
					
						 | 
						 | 
						ishlg.i | 
						⊢ 𝐼  =  ( Itv ‘ 𝐺 )  | 
					
					
						 | 
						 | 
						ishlg.k | 
						⊢ 𝐾  =  ( hlG ‘ 𝐺 )  | 
					
					
						 | 
						 | 
						ishlg.a | 
						⊢ ( 𝜑  →  𝐴  ∈  𝑃 )  | 
					
					
						 | 
						 | 
						ishlg.b | 
						⊢ ( 𝜑  →  𝐵  ∈  𝑃 )  | 
					
					
						 | 
						 | 
						ishlg.c | 
						⊢ ( 𝜑  →  𝐶  ∈  𝑃 )  | 
					
					
						 | 
						 | 
						hlln.1 | 
						⊢ ( 𝜑  →  𝐺  ∈  TarskiG )  | 
					
					
						 | 
						 | 
						hlid.1 | 
						⊢ ( 𝜑  →  𝐴  ≠  𝐶 )  | 
					
				
					 | 
					Assertion | 
					hlid | 
					⊢  ( 𝜑  →  𝐴 ( 𝐾 ‘ 𝐶 ) 𝐴 )  | 
				
			
		
		
			
				Proof
				
					
						| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							ishlg.p | 
							⊢ 𝑃  =  ( Base ‘ 𝐺 )  | 
						
						
							| 2 | 
							
								
							 | 
							ishlg.i | 
							⊢ 𝐼  =  ( Itv ‘ 𝐺 )  | 
						
						
							| 3 | 
							
								
							 | 
							ishlg.k | 
							⊢ 𝐾  =  ( hlG ‘ 𝐺 )  | 
						
						
							| 4 | 
							
								
							 | 
							ishlg.a | 
							⊢ ( 𝜑  →  𝐴  ∈  𝑃 )  | 
						
						
							| 5 | 
							
								
							 | 
							ishlg.b | 
							⊢ ( 𝜑  →  𝐵  ∈  𝑃 )  | 
						
						
							| 6 | 
							
								
							 | 
							ishlg.c | 
							⊢ ( 𝜑  →  𝐶  ∈  𝑃 )  | 
						
						
							| 7 | 
							
								
							 | 
							hlln.1 | 
							⊢ ( 𝜑  →  𝐺  ∈  TarskiG )  | 
						
						
							| 8 | 
							
								
							 | 
							hlid.1 | 
							⊢ ( 𝜑  →  𝐴  ≠  𝐶 )  | 
						
						
							| 9 | 
							
								
							 | 
							eqid | 
							⊢ ( dist ‘ 𝐺 )  =  ( dist ‘ 𝐺 )  | 
						
						
							| 10 | 
							
								1 9 2 7 6 4
							 | 
							tgbtwntriv2 | 
							⊢ ( 𝜑  →  𝐴  ∈  ( 𝐶 𝐼 𝐴 ) )  | 
						
						
							| 11 | 
							
								10
							 | 
							olcd | 
							⊢ ( 𝜑  →  ( 𝐴  ∈  ( 𝐶 𝐼 𝐴 )  ∨  𝐴  ∈  ( 𝐶 𝐼 𝐴 ) ) )  | 
						
						
							| 12 | 
							
								1 2 3 4 4 6 7
							 | 
							ishlg | 
							⊢ ( 𝜑  →  ( 𝐴 ( 𝐾 ‘ 𝐶 ) 𝐴  ↔  ( 𝐴  ≠  𝐶  ∧  𝐴  ≠  𝐶  ∧  ( 𝐴  ∈  ( 𝐶 𝐼 𝐴 )  ∨  𝐴  ∈  ( 𝐶 𝐼 𝐴 ) ) ) ) )  | 
						
						
							| 13 | 
							
								8 8 11 12
							 | 
							mpbir3and | 
							⊢ ( 𝜑  →  𝐴 ( 𝐾 ‘ 𝐶 ) 𝐴 )  |