Metamath Proof Explorer
		
		
		
		Description:  Theorem 19.29 of Margaris p. 90.  See also 19.29r .  (Contributed by NM, 21-Jun-1993)  (Proof shortened by Andrew Salmon, 13-May-2011)
		
			
				
					|  |  | Ref | Expression | 
				
					|  | Assertion | 19.29 |  | 
			
		
		
			
				Proof
				
					
						| Step | Hyp | Ref | Expression | 
						
							| 1 |  | pm3.2 |  | 
						
							| 2 | 1 | aleximi |  | 
						
							| 3 | 2 | imp |  |