| Step | Hyp | Ref | Expression | 
						
							| 1 |  | hdmap12c.h | ⊢ 𝐻  =  ( LHyp ‘ 𝐾 ) | 
						
							| 2 |  | hdmap12c.u | ⊢ 𝑈  =  ( ( DVecH ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 3 |  | hdmap12c.v | ⊢ 𝑉  =  ( Base ‘ 𝑈 ) | 
						
							| 4 |  | hdmap12c.m | ⊢  −   =  ( -g ‘ 𝑈 ) | 
						
							| 5 |  | hdmap12c.c | ⊢ 𝐶  =  ( ( LCDual ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 6 |  | hdmap12c.n | ⊢ 𝑁  =  ( -g ‘ 𝐶 ) | 
						
							| 7 |  | hdmap12c.s | ⊢ 𝑆  =  ( ( HDMap ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 8 |  | hdmap12c.k | ⊢ ( 𝜑  →  ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 ) ) | 
						
							| 9 |  | hdmap12c.x | ⊢ ( 𝜑  →  𝑋  ∈  𝑉 ) | 
						
							| 10 |  | hdmap12c.y | ⊢ ( 𝜑  →  𝑌  ∈  𝑉 ) | 
						
							| 11 |  | eqid | ⊢ ( +g ‘ 𝑈 )  =  ( +g ‘ 𝑈 ) | 
						
							| 12 |  | eqid | ⊢ ( invg ‘ 𝑈 )  =  ( invg ‘ 𝑈 ) | 
						
							| 13 | 3 11 12 4 | grpsubval | ⊢ ( ( 𝑋  ∈  𝑉  ∧  𝑌  ∈  𝑉 )  →  ( 𝑋  −  𝑌 )  =  ( 𝑋 ( +g ‘ 𝑈 ) ( ( invg ‘ 𝑈 ) ‘ 𝑌 ) ) ) | 
						
							| 14 | 9 10 13 | syl2anc | ⊢ ( 𝜑  →  ( 𝑋  −  𝑌 )  =  ( 𝑋 ( +g ‘ 𝑈 ) ( ( invg ‘ 𝑈 ) ‘ 𝑌 ) ) ) | 
						
							| 15 | 14 | fveq2d | ⊢ ( 𝜑  →  ( 𝑆 ‘ ( 𝑋  −  𝑌 ) )  =  ( 𝑆 ‘ ( 𝑋 ( +g ‘ 𝑈 ) ( ( invg ‘ 𝑈 ) ‘ 𝑌 ) ) ) ) | 
						
							| 16 |  | eqid | ⊢ ( +g ‘ 𝐶 )  =  ( +g ‘ 𝐶 ) | 
						
							| 17 | 1 2 8 | dvhlmod | ⊢ ( 𝜑  →  𝑈  ∈  LMod ) | 
						
							| 18 | 3 12 | lmodvnegcl | ⊢ ( ( 𝑈  ∈  LMod  ∧  𝑌  ∈  𝑉 )  →  ( ( invg ‘ 𝑈 ) ‘ 𝑌 )  ∈  𝑉 ) | 
						
							| 19 | 17 10 18 | syl2anc | ⊢ ( 𝜑  →  ( ( invg ‘ 𝑈 ) ‘ 𝑌 )  ∈  𝑉 ) | 
						
							| 20 | 1 2 3 11 5 16 7 8 9 19 | hdmapadd | ⊢ ( 𝜑  →  ( 𝑆 ‘ ( 𝑋 ( +g ‘ 𝑈 ) ( ( invg ‘ 𝑈 ) ‘ 𝑌 ) ) )  =  ( ( 𝑆 ‘ 𝑋 ) ( +g ‘ 𝐶 ) ( 𝑆 ‘ ( ( invg ‘ 𝑈 ) ‘ 𝑌 ) ) ) ) | 
						
							| 21 |  | eqid | ⊢ ( invg ‘ 𝐶 )  =  ( invg ‘ 𝐶 ) | 
						
							| 22 | 1 2 3 12 5 21 7 8 10 | hdmapneg | ⊢ ( 𝜑  →  ( 𝑆 ‘ ( ( invg ‘ 𝑈 ) ‘ 𝑌 ) )  =  ( ( invg ‘ 𝐶 ) ‘ ( 𝑆 ‘ 𝑌 ) ) ) | 
						
							| 23 | 22 | oveq2d | ⊢ ( 𝜑  →  ( ( 𝑆 ‘ 𝑋 ) ( +g ‘ 𝐶 ) ( 𝑆 ‘ ( ( invg ‘ 𝑈 ) ‘ 𝑌 ) ) )  =  ( ( 𝑆 ‘ 𝑋 ) ( +g ‘ 𝐶 ) ( ( invg ‘ 𝐶 ) ‘ ( 𝑆 ‘ 𝑌 ) ) ) ) | 
						
							| 24 | 15 20 23 | 3eqtrd | ⊢ ( 𝜑  →  ( 𝑆 ‘ ( 𝑋  −  𝑌 ) )  =  ( ( 𝑆 ‘ 𝑋 ) ( +g ‘ 𝐶 ) ( ( invg ‘ 𝐶 ) ‘ ( 𝑆 ‘ 𝑌 ) ) ) ) | 
						
							| 25 |  | eqid | ⊢ ( Base ‘ 𝐶 )  =  ( Base ‘ 𝐶 ) | 
						
							| 26 | 1 2 3 5 25 7 8 9 | hdmapcl | ⊢ ( 𝜑  →  ( 𝑆 ‘ 𝑋 )  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 27 | 1 2 3 5 25 7 8 10 | hdmapcl | ⊢ ( 𝜑  →  ( 𝑆 ‘ 𝑌 )  ∈  ( Base ‘ 𝐶 ) ) | 
						
							| 28 | 25 16 21 6 | grpsubval | ⊢ ( ( ( 𝑆 ‘ 𝑋 )  ∈  ( Base ‘ 𝐶 )  ∧  ( 𝑆 ‘ 𝑌 )  ∈  ( Base ‘ 𝐶 ) )  →  ( ( 𝑆 ‘ 𝑋 ) 𝑁 ( 𝑆 ‘ 𝑌 ) )  =  ( ( 𝑆 ‘ 𝑋 ) ( +g ‘ 𝐶 ) ( ( invg ‘ 𝐶 ) ‘ ( 𝑆 ‘ 𝑌 ) ) ) ) | 
						
							| 29 | 26 27 28 | syl2anc | ⊢ ( 𝜑  →  ( ( 𝑆 ‘ 𝑋 ) 𝑁 ( 𝑆 ‘ 𝑌 ) )  =  ( ( 𝑆 ‘ 𝑋 ) ( +g ‘ 𝐶 ) ( ( invg ‘ 𝐶 ) ‘ ( 𝑆 ‘ 𝑌 ) ) ) ) | 
						
							| 30 | 24 29 | eqtr4d | ⊢ ( 𝜑  →  ( 𝑆 ‘ ( 𝑋  −  𝑌 ) )  =  ( ( 𝑆 ‘ 𝑋 ) 𝑁 ( 𝑆 ‘ 𝑌 ) ) ) |