Metamath Proof Explorer
		
		
		
		Description:  Existence of the class of values of a set.  (Contributed by NM, 9-Nov-1995)
		
			
				
					|  |  | Ref | Expression | 
					
						|  | Hypothesis | fvclex.1 | ⊢ 𝐹  ∈  V | 
				
					|  | Assertion | fvclex | ⊢  { 𝑦  ∣  ∃ 𝑥 𝑦  =  ( 𝐹 ‘ 𝑥 ) }  ∈  V | 
			
		
		
			
				Proof
				
					
						| Step | Hyp | Ref | Expression | 
						
							| 1 |  | fvclex.1 | ⊢ 𝐹  ∈  V | 
						
							| 2 | 1 | rnex | ⊢ ran  𝐹  ∈  V | 
						
							| 3 |  | snex | ⊢ { ∅ }  ∈  V | 
						
							| 4 | 2 3 | unex | ⊢ ( ran  𝐹  ∪  { ∅ } )  ∈  V | 
						
							| 5 |  | fvclss | ⊢ { 𝑦  ∣  ∃ 𝑥 𝑦  =  ( 𝐹 ‘ 𝑥 ) }  ⊆  ( ran  𝐹  ∪  { ∅ } ) | 
						
							| 6 | 4 5 | ssexi | ⊢ { 𝑦  ∣  ∃ 𝑥 𝑦  =  ( 𝐹 ‘ 𝑥 ) }  ∈  V |