| Step | Hyp | Ref | Expression | 
						
							| 1 |  | nvinvfval.2 | ⊢ 𝐺  =  (  +𝑣  ‘ 𝑈 ) | 
						
							| 2 |  | nvinvfval.4 | ⊢ 𝑆  =  (  ·𝑠OLD  ‘ 𝑈 ) | 
						
							| 3 |  | nvinvfval.3 | ⊢ 𝑁  =  ( 𝑆  ∘  ◡ ( 2nd   ↾  ( { - 1 }  ×  V ) ) ) | 
						
							| 4 |  | eqid | ⊢ ( BaseSet ‘ 𝑈 )  =  ( BaseSet ‘ 𝑈 ) | 
						
							| 5 | 4 2 | nvsf | ⊢ ( 𝑈  ∈  NrmCVec  →  𝑆 : ( ℂ  ×  ( BaseSet ‘ 𝑈 ) ) ⟶ ( BaseSet ‘ 𝑈 ) ) | 
						
							| 6 |  | neg1cn | ⊢ - 1  ∈  ℂ | 
						
							| 7 | 3 | curry1f | ⊢ ( ( 𝑆 : ( ℂ  ×  ( BaseSet ‘ 𝑈 ) ) ⟶ ( BaseSet ‘ 𝑈 )  ∧  - 1  ∈  ℂ )  →  𝑁 : ( BaseSet ‘ 𝑈 ) ⟶ ( BaseSet ‘ 𝑈 ) ) | 
						
							| 8 | 5 6 7 | sylancl | ⊢ ( 𝑈  ∈  NrmCVec  →  𝑁 : ( BaseSet ‘ 𝑈 ) ⟶ ( BaseSet ‘ 𝑈 ) ) | 
						
							| 9 | 8 | ffnd | ⊢ ( 𝑈  ∈  NrmCVec  →  𝑁  Fn  ( BaseSet ‘ 𝑈 ) ) | 
						
							| 10 | 1 | nvgrp | ⊢ ( 𝑈  ∈  NrmCVec  →  𝐺  ∈  GrpOp ) | 
						
							| 11 | 4 1 | bafval | ⊢ ( BaseSet ‘ 𝑈 )  =  ran  𝐺 | 
						
							| 12 |  | eqid | ⊢ ( inv ‘ 𝐺 )  =  ( inv ‘ 𝐺 ) | 
						
							| 13 | 11 12 | grpoinvf | ⊢ ( 𝐺  ∈  GrpOp  →  ( inv ‘ 𝐺 ) : ( BaseSet ‘ 𝑈 ) –1-1-onto→ ( BaseSet ‘ 𝑈 ) ) | 
						
							| 14 |  | f1ofn | ⊢ ( ( inv ‘ 𝐺 ) : ( BaseSet ‘ 𝑈 ) –1-1-onto→ ( BaseSet ‘ 𝑈 )  →  ( inv ‘ 𝐺 )  Fn  ( BaseSet ‘ 𝑈 ) ) | 
						
							| 15 | 10 13 14 | 3syl | ⊢ ( 𝑈  ∈  NrmCVec  →  ( inv ‘ 𝐺 )  Fn  ( BaseSet ‘ 𝑈 ) ) | 
						
							| 16 | 5 | ffnd | ⊢ ( 𝑈  ∈  NrmCVec  →  𝑆  Fn  ( ℂ  ×  ( BaseSet ‘ 𝑈 ) ) ) | 
						
							| 17 | 16 | adantr | ⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝑥  ∈  ( BaseSet ‘ 𝑈 ) )  →  𝑆  Fn  ( ℂ  ×  ( BaseSet ‘ 𝑈 ) ) ) | 
						
							| 18 | 3 | curry1val | ⊢ ( ( 𝑆  Fn  ( ℂ  ×  ( BaseSet ‘ 𝑈 ) )  ∧  - 1  ∈  ℂ )  →  ( 𝑁 ‘ 𝑥 )  =  ( - 1 𝑆 𝑥 ) ) | 
						
							| 19 | 17 6 18 | sylancl | ⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝑥  ∈  ( BaseSet ‘ 𝑈 ) )  →  ( 𝑁 ‘ 𝑥 )  =  ( - 1 𝑆 𝑥 ) ) | 
						
							| 20 | 4 1 2 12 | nvinv | ⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝑥  ∈  ( BaseSet ‘ 𝑈 ) )  →  ( - 1 𝑆 𝑥 )  =  ( ( inv ‘ 𝐺 ) ‘ 𝑥 ) ) | 
						
							| 21 | 19 20 | eqtrd | ⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝑥  ∈  ( BaseSet ‘ 𝑈 ) )  →  ( 𝑁 ‘ 𝑥 )  =  ( ( inv ‘ 𝐺 ) ‘ 𝑥 ) ) | 
						
							| 22 | 9 15 21 | eqfnfvd | ⊢ ( 𝑈  ∈  NrmCVec  →  𝑁  =  ( inv ‘ 𝐺 ) ) |