Metamath Proof Explorer
		
		
		
		Description:  Define reflexive relation; relation R is reflexive over the set
       A iff A. x e. A x R x .  (Contributed by David A. Wheeler, 1-Dec-2019)
		
			
				
					 | 
					 | 
					Ref | 
					Expression | 
				
				
					 | 
					Assertion | 
					df-reflexive | 
					⊢  ( 𝑅 Reflexive 𝐴  ↔  ( 𝑅  ⊆  ( 𝐴  ×  𝐴 )  ∧  ∀ 𝑥  ∈  𝐴 𝑥 𝑅 𝑥 ) )  | 
				
			
		
		
			
				Detailed syntax breakdown
				
					
						| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 0 | 
							
								
							 | 
							cR | 
							⊢ 𝑅  | 
						
						
							| 1 | 
							
								
							 | 
							cA | 
							⊢ 𝐴  | 
						
						
							| 2 | 
							
								1 0
							 | 
							wreflexive | 
							⊢ 𝑅 Reflexive 𝐴  | 
						
						
							| 3 | 
							
								1 1
							 | 
							cxp | 
							⊢ ( 𝐴  ×  𝐴 )  | 
						
						
							| 4 | 
							
								0 3
							 | 
							wss | 
							⊢ 𝑅  ⊆  ( 𝐴  ×  𝐴 )  | 
						
						
							| 5 | 
							
								
							 | 
							vx | 
							⊢ 𝑥  | 
						
						
							| 6 | 
							
								5
							 | 
							cv | 
							⊢ 𝑥  | 
						
						
							| 7 | 
							
								6 6 0
							 | 
							wbr | 
							⊢ 𝑥 𝑅 𝑥  | 
						
						
							| 8 | 
							
								7 5 1
							 | 
							wral | 
							⊢ ∀ 𝑥  ∈  𝐴 𝑥 𝑅 𝑥  | 
						
						
							| 9 | 
							
								4 8
							 | 
							wa | 
							⊢ ( 𝑅  ⊆  ( 𝐴  ×  𝐴 )  ∧  ∀ 𝑥  ∈  𝐴 𝑥 𝑅 𝑥 )  | 
						
						
							| 10 | 
							
								2 9
							 | 
							wb | 
							⊢ ( 𝑅 Reflexive 𝐴  ↔  ( 𝑅  ⊆  ( 𝐴  ×  𝐴 )  ∧  ∀ 𝑥  ∈  𝐴 𝑥 𝑅 𝑥 ) )  |