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 ) ) |