Database ZF (ZERMELO-FRAENKEL) SET THEORY ZF Set Theory - add the Axiom of Union Recursive definition generator rdgfnon  
				
		 
		
			
		 
		Description:   The recursive definition generator is a function on ordinal numbers.
       (Contributed by NM , 9-Apr-1995)   (Revised by Mario Carneiro , 9-May-2015) 
		
			
				
					Ref 
					Expression 
				 
				
					Assertion 
					rdgfnon   ⊢    rec  ⁡   F  A      Fn  On       
				 
			
		 
		
				Proof 
				
					
						Step 
						Hyp 
						Ref 
						Expression 
					 
						
							1 
								
							 
							df-rdg  ⊢    rec  ⁡   F  A      =   recs  ⁡    g  ∈  V  ⟼   if   g  =  ∅    A   if   Lim  ⁡   dom  ⁡  g       ⋃   ran  ⁡  g       F  ⁡   g  ⁡   ⋃   dom  ⁡  g                   
						
							2 
								1 
							 
							tfr1  ⊢    rec  ⁡   F  A      Fn  On