Metamath Proof Explorer
		
		
		
		Description:  Example for df-eprel .  Example by David A. Wheeler.  (Contributed by Mario Carneiro, 18-Jun-2015)
		
			
				
					|  |  | Ref | Expression | 
				
					|  | Assertion | ex-eprel |  | 
			
		
		
			
				Proof
				
					
						| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 5nn |  | 
						
							| 2 | 1 | elexi |  | 
						
							| 3 | 2 | prid2 |  | 
						
							| 4 |  | prex |  | 
						
							| 5 | 4 | epeli |  | 
						
							| 6 | 3 5 | mpbir |  |