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 | 
							   |