| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ntrnei.o | ⊢ 𝑂  =  ( 𝑖  ∈  V ,  𝑗  ∈  V  ↦  ( 𝑘  ∈  ( 𝒫  𝑗  ↑m  𝑖 )  ↦  ( 𝑙  ∈  𝑗  ↦  { 𝑚  ∈  𝑖  ∣  𝑙  ∈  ( 𝑘 ‘ 𝑚 ) } ) ) ) | 
						
							| 2 |  | ntrnei.f | ⊢ 𝐹  =  ( 𝒫  𝐵 𝑂 𝐵 ) | 
						
							| 3 |  | ntrnei.r | ⊢ ( 𝜑  →  𝐼 𝐹 𝑁 ) | 
						
							| 4 |  | ntrnei.x | ⊢ ( 𝜑  →  𝑋  ∈  𝐵 ) | 
						
							| 5 |  | ntrnei.s | ⊢ ( 𝜑  →  𝑆  ∈  𝒫  𝐵 ) | 
						
							| 6 |  | fveq2 | ⊢ ( 𝑚  =  𝑆  →  ( 𝐼 ‘ 𝑚 )  =  ( 𝐼 ‘ 𝑆 ) ) | 
						
							| 7 | 6 | eleq2d | ⊢ ( 𝑚  =  𝑆  →  ( 𝑋  ∈  ( 𝐼 ‘ 𝑚 )  ↔  𝑋  ∈  ( 𝐼 ‘ 𝑆 ) ) ) | 
						
							| 8 | 7 | elrab3 | ⊢ ( 𝑆  ∈  𝒫  𝐵  →  ( 𝑆  ∈  { 𝑚  ∈  𝒫  𝐵  ∣  𝑋  ∈  ( 𝐼 ‘ 𝑚 ) }  ↔  𝑋  ∈  ( 𝐼 ‘ 𝑆 ) ) ) | 
						
							| 9 | 5 8 | syl | ⊢ ( 𝜑  →  ( 𝑆  ∈  { 𝑚  ∈  𝒫  𝐵  ∣  𝑋  ∈  ( 𝐼 ‘ 𝑚 ) }  ↔  𝑋  ∈  ( 𝐼 ‘ 𝑆 ) ) ) | 
						
							| 10 | 1 2 3 | ntrneibex | ⊢ ( 𝜑  →  𝐵  ∈  V ) | 
						
							| 11 | 10 | pwexd | ⊢ ( 𝜑  →  𝒫  𝐵  ∈  V ) | 
						
							| 12 | 1 2 3 | ntrneiiex | ⊢ ( 𝜑  →  𝐼  ∈  ( 𝒫  𝐵  ↑m  𝒫  𝐵 ) ) | 
						
							| 13 |  | eqid | ⊢ ( 𝐹 ‘ 𝐼 )  =  ( 𝐹 ‘ 𝐼 ) | 
						
							| 14 | 1 11 10 2 12 13 4 | fsovfvfvd | ⊢ ( 𝜑  →  ( ( 𝐹 ‘ 𝐼 ) ‘ 𝑋 )  =  { 𝑚  ∈  𝒫  𝐵  ∣  𝑋  ∈  ( 𝐼 ‘ 𝑚 ) } ) | 
						
							| 15 | 1 2 3 | ntrneifv1 | ⊢ ( 𝜑  →  ( 𝐹 ‘ 𝐼 )  =  𝑁 ) | 
						
							| 16 | 15 | fveq1d | ⊢ ( 𝜑  →  ( ( 𝐹 ‘ 𝐼 ) ‘ 𝑋 )  =  ( 𝑁 ‘ 𝑋 ) ) | 
						
							| 17 | 14 16 | eqtr3d | ⊢ ( 𝜑  →  { 𝑚  ∈  𝒫  𝐵  ∣  𝑋  ∈  ( 𝐼 ‘ 𝑚 ) }  =  ( 𝑁 ‘ 𝑋 ) ) | 
						
							| 18 | 17 | eleq2d | ⊢ ( 𝜑  →  ( 𝑆  ∈  { 𝑚  ∈  𝒫  𝐵  ∣  𝑋  ∈  ( 𝐼 ‘ 𝑚 ) }  ↔  𝑆  ∈  ( 𝑁 ‘ 𝑋 ) ) ) | 
						
							| 19 | 9 18 | bitr3d | ⊢ ( 𝜑  →  ( 𝑋  ∈  ( 𝐼 ‘ 𝑆 )  ↔  𝑆  ∈  ( 𝑁 ‘ 𝑋 ) ) ) |