Database GRAPH THEORY Vertices and edges Vertices and indexed edges The vertices and edges of a graph represented as ordered pair opvtxfvi  
				
		 
		
			
		 
		Description:   The set of vertices of a graph represented as an ordered pair of
       vertices and indexed edges as function value.  (Contributed by AV , 4-Mar-2021) 
		
			
				
					Ref 
					Expression 
				 
					
						Hypotheses 
						opvtxfvi.v   ⊢   V  ∈  V       
					 
					
						opvtxfvi.e   ⊢   E  ∈  V       
					 
				
					Assertion 
					opvtxfvi   ⊢     Vtx   ⁡   V  E     =  V       
				 
			
		 
		
				Proof 
				
					
						Step 
						Hyp 
						Ref 
						Expression 
					 
						
							1 
								
							 
							opvtxfvi.v  ⊢   V  ∈  V       
						
							2 
								
							 
							opvtxfvi.e  ⊢   E  ∈  V       
						
							3 
								
							 
							opvtxfv   ⊢    V  ∈  V    ∧   E  ∈  V     →     Vtx   ⁡   V  E     =  V         
						
							4 
								1  2  3 
							 
							mp2an  ⊢     Vtx   ⁡   V  E     =  V