| Step | Hyp | Ref | Expression | 
						
							| 1 |  | hlhilip.h | ⊢ 𝐻  =  ( LHyp ‘ 𝐾 ) | 
						
							| 2 |  | hlhilip.l | ⊢ 𝐿  =  ( ( DVecH ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 3 |  | hlhilip.v | ⊢ 𝑉  =  ( Base ‘ 𝐿 ) | 
						
							| 4 |  | hlhilip.s | ⊢ 𝑆  =  ( ( HDMap ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 5 |  | hlhilip.u | ⊢ 𝑈  =  ( ( HLHil ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 6 |  | hlhilip.k | ⊢ ( 𝜑  →  ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 ) ) | 
						
							| 7 |  | hlhilip.i | ⊢  ,   =  ( ·𝑖 ‘ 𝑈 ) | 
						
							| 8 |  | hlhilip.x | ⊢ ( 𝜑  →  𝑋  ∈  𝑉 ) | 
						
							| 9 |  | hlhilip.y | ⊢ ( 𝜑  →  𝑌  ∈  𝑉 ) | 
						
							| 10 |  | eqid | ⊢ ( 𝑥  ∈  𝑉 ,  𝑦  ∈  𝑉  ↦  ( ( 𝑆 ‘ 𝑦 ) ‘ 𝑥 ) )  =  ( 𝑥  ∈  𝑉 ,  𝑦  ∈  𝑉  ↦  ( ( 𝑆 ‘ 𝑦 ) ‘ 𝑥 ) ) | 
						
							| 11 | 1 2 3 4 5 6 10 | hlhilip | ⊢ ( 𝜑  →  ( 𝑥  ∈  𝑉 ,  𝑦  ∈  𝑉  ↦  ( ( 𝑆 ‘ 𝑦 ) ‘ 𝑥 ) )  =  ( ·𝑖 ‘ 𝑈 ) ) | 
						
							| 12 | 7 11 | eqtr4id | ⊢ ( 𝜑  →   ,   =  ( 𝑥  ∈  𝑉 ,  𝑦  ∈  𝑉  ↦  ( ( 𝑆 ‘ 𝑦 ) ‘ 𝑥 ) ) ) | 
						
							| 13 | 12 | oveqd | ⊢ ( 𝜑  →  ( 𝑋  ,  𝑌 )  =  ( 𝑋 ( 𝑥  ∈  𝑉 ,  𝑦  ∈  𝑉  ↦  ( ( 𝑆 ‘ 𝑦 ) ‘ 𝑥 ) ) 𝑌 ) ) | 
						
							| 14 |  | fveq2 | ⊢ ( 𝑥  =  𝑋  →  ( ( 𝑆 ‘ 𝑦 ) ‘ 𝑥 )  =  ( ( 𝑆 ‘ 𝑦 ) ‘ 𝑋 ) ) | 
						
							| 15 |  | fveq2 | ⊢ ( 𝑦  =  𝑌  →  ( 𝑆 ‘ 𝑦 )  =  ( 𝑆 ‘ 𝑌 ) ) | 
						
							| 16 | 15 | fveq1d | ⊢ ( 𝑦  =  𝑌  →  ( ( 𝑆 ‘ 𝑦 ) ‘ 𝑋 )  =  ( ( 𝑆 ‘ 𝑌 ) ‘ 𝑋 ) ) | 
						
							| 17 |  | fvex | ⊢ ( ( 𝑆 ‘ 𝑌 ) ‘ 𝑋 )  ∈  V | 
						
							| 18 | 14 16 10 17 | ovmpo | ⊢ ( ( 𝑋  ∈  𝑉  ∧  𝑌  ∈  𝑉 )  →  ( 𝑋 ( 𝑥  ∈  𝑉 ,  𝑦  ∈  𝑉  ↦  ( ( 𝑆 ‘ 𝑦 ) ‘ 𝑥 ) ) 𝑌 )  =  ( ( 𝑆 ‘ 𝑌 ) ‘ 𝑋 ) ) | 
						
							| 19 | 8 9 18 | syl2anc | ⊢ ( 𝜑  →  ( 𝑋 ( 𝑥  ∈  𝑉 ,  𝑦  ∈  𝑉  ↦  ( ( 𝑆 ‘ 𝑦 ) ‘ 𝑥 ) ) 𝑌 )  =  ( ( 𝑆 ‘ 𝑌 ) ‘ 𝑋 ) ) | 
						
							| 20 | 13 19 | eqtrd | ⊢ ( 𝜑  →  ( 𝑋  ,  𝑌 )  =  ( ( 𝑆 ‘ 𝑌 ) ‘ 𝑋 ) ) |