Metamath Proof Explorer
		
		
		
		Description:  The relative complement of the class S exists as a subset of the
       base set.  (Contributed by RP, 25-Jun-2021)
		
			
				
					|  |  | Ref | Expression | 
					
						|  | Hypotheses | ntrclsbex.d | ⊢ 𝐷  =  ( 𝑂 ‘ 𝐵 ) | 
					
						|  |  | ntrclsbex.r | ⊢ ( 𝜑  →  𝐼 𝐷 𝐾 ) | 
				
					|  | Assertion | ntrclsrcomplex | ⊢  ( 𝜑  →  ( 𝐵  ∖  𝑆 )  ∈  𝒫  𝐵 ) | 
			
		
		
			
				Proof
				
					
						| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ntrclsbex.d | ⊢ 𝐷  =  ( 𝑂 ‘ 𝐵 ) | 
						
							| 2 |  | ntrclsbex.r | ⊢ ( 𝜑  →  𝐼 𝐷 𝐾 ) | 
						
							| 3 | 1 2 | ntrclsbex | ⊢ ( 𝜑  →  𝐵  ∈  V ) | 
						
							| 4 |  | difssd | ⊢ ( 𝜑  →  ( 𝐵  ∖  𝑆 )  ⊆  𝐵 ) | 
						
							| 5 | 3 4 | sselpwd | ⊢ ( 𝜑  →  ( 𝐵  ∖  𝑆 )  ∈  𝒫  𝐵 ) |