| Step | Hyp | Ref | Expression | 
						
							| 1 |  | grpvlinv.b | ⊢ 𝐵  =  ( Base ‘ 𝐺 ) | 
						
							| 2 |  | grpvlinv.p | ⊢  +   =  ( +g ‘ 𝐺 ) | 
						
							| 3 |  | grpvlinv.n | ⊢ 𝑁  =  ( invg ‘ 𝐺 ) | 
						
							| 4 |  | grpvlinv.z | ⊢  0   =  ( 0g ‘ 𝐺 ) | 
						
							| 5 |  | elmapex | ⊢ ( 𝑋  ∈  ( 𝐵  ↑m  𝐼 )  →  ( 𝐵  ∈  V  ∧  𝐼  ∈  V ) ) | 
						
							| 6 | 5 | simprd | ⊢ ( 𝑋  ∈  ( 𝐵  ↑m  𝐼 )  →  𝐼  ∈  V ) | 
						
							| 7 | 6 | adantl | ⊢ ( ( 𝐺  ∈  Grp  ∧  𝑋  ∈  ( 𝐵  ↑m  𝐼 ) )  →  𝐼  ∈  V ) | 
						
							| 8 |  | elmapi | ⊢ ( 𝑋  ∈  ( 𝐵  ↑m  𝐼 )  →  𝑋 : 𝐼 ⟶ 𝐵 ) | 
						
							| 9 | 8 | adantl | ⊢ ( ( 𝐺  ∈  Grp  ∧  𝑋  ∈  ( 𝐵  ↑m  𝐼 ) )  →  𝑋 : 𝐼 ⟶ 𝐵 ) | 
						
							| 10 | 1 4 | grpidcl | ⊢ ( 𝐺  ∈  Grp  →   0   ∈  𝐵 ) | 
						
							| 11 | 10 | adantr | ⊢ ( ( 𝐺  ∈  Grp  ∧  𝑋  ∈  ( 𝐵  ↑m  𝐼 ) )  →   0   ∈  𝐵 ) | 
						
							| 12 | 1 3 | grpinvf | ⊢ ( 𝐺  ∈  Grp  →  𝑁 : 𝐵 ⟶ 𝐵 ) | 
						
							| 13 | 12 | adantr | ⊢ ( ( 𝐺  ∈  Grp  ∧  𝑋  ∈  ( 𝐵  ↑m  𝐼 ) )  →  𝑁 : 𝐵 ⟶ 𝐵 ) | 
						
							| 14 |  | fcompt | ⊢ ( ( 𝑁 : 𝐵 ⟶ 𝐵  ∧  𝑋 : 𝐼 ⟶ 𝐵 )  →  ( 𝑁  ∘  𝑋 )  =  ( 𝑥  ∈  𝐼  ↦  ( 𝑁 ‘ ( 𝑋 ‘ 𝑥 ) ) ) ) | 
						
							| 15 | 12 8 14 | syl2an | ⊢ ( ( 𝐺  ∈  Grp  ∧  𝑋  ∈  ( 𝐵  ↑m  𝐼 ) )  →  ( 𝑁  ∘  𝑋 )  =  ( 𝑥  ∈  𝐼  ↦  ( 𝑁 ‘ ( 𝑋 ‘ 𝑥 ) ) ) ) | 
						
							| 16 | 1 2 4 3 | grplinv | ⊢ ( ( 𝐺  ∈  Grp  ∧  𝑦  ∈  𝐵 )  →  ( ( 𝑁 ‘ 𝑦 )  +  𝑦 )  =   0  ) | 
						
							| 17 | 16 | adantlr | ⊢ ( ( ( 𝐺  ∈  Grp  ∧  𝑋  ∈  ( 𝐵  ↑m  𝐼 ) )  ∧  𝑦  ∈  𝐵 )  →  ( ( 𝑁 ‘ 𝑦 )  +  𝑦 )  =   0  ) | 
						
							| 18 | 7 9 11 13 15 17 | caofinvl | ⊢ ( ( 𝐺  ∈  Grp  ∧  𝑋  ∈  ( 𝐵  ↑m  𝐼 ) )  →  ( ( 𝑁  ∘  𝑋 )  ∘f   +  𝑋 )  =  ( 𝐼  ×  {  0  } ) ) |