| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							nvmval.1 | 
							⊢ 𝑋  =  ( BaseSet ‘ 𝑈 )  | 
						
						
							| 2 | 
							
								
							 | 
							nvmval.2 | 
							⊢ 𝐺  =  (  +𝑣  ‘ 𝑈 )  | 
						
						
							| 3 | 
							
								
							 | 
							nvmval.4 | 
							⊢ 𝑆  =  (  ·𝑠OLD  ‘ 𝑈 )  | 
						
						
							| 4 | 
							
								
							 | 
							nvmval.3 | 
							⊢ 𝑀  =  (  −𝑣  ‘ 𝑈 )  | 
						
						
							| 5 | 
							
								2
							 | 
							nvgrp | 
							⊢ ( 𝑈  ∈  NrmCVec  →  𝐺  ∈  GrpOp )  | 
						
						
							| 6 | 
							
								1 2
							 | 
							bafval | 
							⊢ 𝑋  =  ran  𝐺  | 
						
						
							| 7 | 
							
								
							 | 
							eqid | 
							⊢ ( inv ‘ 𝐺 )  =  ( inv ‘ 𝐺 )  | 
						
						
							| 8 | 
							
								2 4
							 | 
							vsfval | 
							⊢ 𝑀  =  (  /𝑔  ‘ 𝐺 )  | 
						
						
							| 9 | 
							
								6 7 8
							 | 
							grpodivfval | 
							⊢ ( 𝐺  ∈  GrpOp  →  𝑀  =  ( 𝑥  ∈  𝑋 ,  𝑦  ∈  𝑋  ↦  ( 𝑥 𝐺 ( ( inv ‘ 𝐺 ) ‘ 𝑦 ) ) ) )  | 
						
						
							| 10 | 
							
								5 9
							 | 
							syl | 
							⊢ ( 𝑈  ∈  NrmCVec  →  𝑀  =  ( 𝑥  ∈  𝑋 ,  𝑦  ∈  𝑋  ↦  ( 𝑥 𝐺 ( ( inv ‘ 𝐺 ) ‘ 𝑦 ) ) ) )  | 
						
						
							| 11 | 
							
								1 2 3 7
							 | 
							nvinv | 
							⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝑦  ∈  𝑋 )  →  ( - 1 𝑆 𝑦 )  =  ( ( inv ‘ 𝐺 ) ‘ 𝑦 ) )  | 
						
						
							| 12 | 
							
								11
							 | 
							3adant2 | 
							⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝑥  ∈  𝑋  ∧  𝑦  ∈  𝑋 )  →  ( - 1 𝑆 𝑦 )  =  ( ( inv ‘ 𝐺 ) ‘ 𝑦 ) )  | 
						
						
							| 13 | 
							
								12
							 | 
							oveq2d | 
							⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝑥  ∈  𝑋  ∧  𝑦  ∈  𝑋 )  →  ( 𝑥 𝐺 ( - 1 𝑆 𝑦 ) )  =  ( 𝑥 𝐺 ( ( inv ‘ 𝐺 ) ‘ 𝑦 ) ) )  | 
						
						
							| 14 | 
							
								13
							 | 
							mpoeq3dva | 
							⊢ ( 𝑈  ∈  NrmCVec  →  ( 𝑥  ∈  𝑋 ,  𝑦  ∈  𝑋  ↦  ( 𝑥 𝐺 ( - 1 𝑆 𝑦 ) ) )  =  ( 𝑥  ∈  𝑋 ,  𝑦  ∈  𝑋  ↦  ( 𝑥 𝐺 ( ( inv ‘ 𝐺 ) ‘ 𝑦 ) ) ) )  | 
						
						
							| 15 | 
							
								10 14
							 | 
							eqtr4d | 
							⊢ ( 𝑈  ∈  NrmCVec  →  𝑀  =  ( 𝑥  ∈  𝑋 ,  𝑦  ∈  𝑋  ↦  ( 𝑥 𝐺 ( - 1 𝑆 𝑦 ) ) ) )  |