Database  
				SUPPLEMENTARY MATERIAL (USERS' MATHBOXES)  
				Mathbox for Steven Nguyen  
				Structures  
				pwselbasr  
			 
				
		 
		 Metamath Proof Explorer 
		
			
		 
		 
		
		Description:   The reverse direction of pwselbasb  : a function between the index and
       base set of a structure is an element of the structure power.
       (Contributed by SN , 29-Jul-2024) 
		
			
				
					 
					 
					Ref 
					Expression 
				 
					
						 
						Hypotheses 
						pwselbasr.y  
						⊢  𝑌   =  ( 𝑅   ↑s    𝐼  )  
					 
					
						 
						 
						pwselbasr.b  
						⊢  𝐵   =  ( Base ‘ 𝑅  )  
					 
					
						 
						 
						pwselbasr.v  
						⊢  𝑉   =  ( Base ‘ 𝑌  )  
					 
					
						 
						 
						pwselbasr.r  
						⊢  ( 𝜑   →  𝑅   ∈  𝑊  )  
					 
					
						 
						 
						pwselbasr.i  
						⊢  ( 𝜑   →  𝐼   ∈  𝑍  )  
					 
					
						 
						 
						pwselbasr.x  
						⊢  ( 𝜑   →  𝑋  : 𝐼  ⟶ 𝐵  )  
					 
				
					 
					Assertion 
					pwselbasr  
					⊢   ( 𝜑   →  𝑋   ∈  𝑉  )  
				 
			
		 
		 
			
				Proof 
				
					
						Step 
						Hyp 
						Ref 
						Expression 
					 
						
							1  
							
								
							 
							pwselbasr.y  
							⊢  𝑌   =  ( 𝑅   ↑s    𝐼  )  
						 
						
							2  
							
								
							 
							pwselbasr.b  
							⊢  𝐵   =  ( Base ‘ 𝑅  )  
						 
						
							3  
							
								
							 
							pwselbasr.v  
							⊢  𝑉   =  ( Base ‘ 𝑌  )  
						 
						
							4  
							
								
							 
							pwselbasr.r  
							⊢  ( 𝜑   →  𝑅   ∈  𝑊  )  
						 
						
							5  
							
								
							 
							pwselbasr.i  
							⊢  ( 𝜑   →  𝐼   ∈  𝑍  )  
						 
						
							6  
							
								
							 
							pwselbasr.x  
							⊢  ( 𝜑   →  𝑋  : 𝐼  ⟶ 𝐵  )  
						 
						
							7  
							
								1  2  3 
							 
							pwselbasb  
							⊢  ( ( 𝑅   ∈  𝑊   ∧  𝐼   ∈  𝑍  )  →  ( 𝑋   ∈  𝑉   ↔  𝑋  : 𝐼  ⟶ 𝐵  ) )  
						 
						
							8  
							
								4  5  7 
							 
							syl2anc  
							⊢  ( 𝜑   →  ( 𝑋   ∈  𝑉   ↔  𝑋  : 𝐼  ⟶ 𝐵  ) )  
						 
						
							9  
							
								6  8 
							 
							mpbird  
							⊢  ( 𝜑   →  𝑋   ∈  𝑉  )