Metamath Proof Explorer
		
		
		
		Description:  Commutation of antecedents.  Swap 1st and 4th.  (Contributed by NM, 25-Apr-1994)  (Proof shortened by Wolf Lammen, 28-Jul-2012)
		
			
				
					|  |  | Ref | Expression | 
					
						|  | Hypothesis | com4.1 |  | 
				
					|  | Assertion | com14 |  | 
			
		
		
			
				Proof
				
					
						| Step | Hyp | Ref | Expression | 
						
							| 1 |  | com4.1 |  | 
						
							| 2 | 1 | com4l |  | 
						
							| 3 | 2 | com3r |  |