| Step | Hyp | Ref | Expression | 
						
							| 1 |  | gsummgmpropd.f | ⊢ ( 𝜑  →  𝐹  ∈  𝑉 ) | 
						
							| 2 |  | gsummgmpropd.g | ⊢ ( 𝜑  →  𝐺  ∈  𝑊 ) | 
						
							| 3 |  | gsummgmpropd.h | ⊢ ( 𝜑  →  𝐻  ∈  𝑋 ) | 
						
							| 4 |  | gsummgmpropd.b | ⊢ ( 𝜑  →  ( Base ‘ 𝐺 )  =  ( Base ‘ 𝐻 ) ) | 
						
							| 5 |  | gsummgmpropd.m | ⊢ ( 𝜑  →  𝐺  ∈  Mgm ) | 
						
							| 6 |  | gsummgmpropd.e | ⊢ ( ( 𝜑  ∧  ( 𝑠  ∈  ( Base ‘ 𝐺 )  ∧  𝑡  ∈  ( Base ‘ 𝐺 ) ) )  →  ( 𝑠 ( +g ‘ 𝐺 ) 𝑡 )  =  ( 𝑠 ( +g ‘ 𝐻 ) 𝑡 ) ) | 
						
							| 7 |  | gsummgmpropd.n | ⊢ ( 𝜑  →  Fun  𝐹 ) | 
						
							| 8 |  | gsummgmpropd.r | ⊢ ( 𝜑  →  ran  𝐹  ⊆  ( Base ‘ 𝐺 ) ) | 
						
							| 9 |  | eqid | ⊢ ( Base ‘ 𝐺 )  =  ( Base ‘ 𝐺 ) | 
						
							| 10 |  | eqid | ⊢ ( +g ‘ 𝐺 )  =  ( +g ‘ 𝐺 ) | 
						
							| 11 | 9 10 | mgmcl | ⊢ ( ( 𝐺  ∈  Mgm  ∧  𝑠  ∈  ( Base ‘ 𝐺 )  ∧  𝑡  ∈  ( Base ‘ 𝐺 ) )  →  ( 𝑠 ( +g ‘ 𝐺 ) 𝑡 )  ∈  ( Base ‘ 𝐺 ) ) | 
						
							| 12 | 11 | 3expib | ⊢ ( 𝐺  ∈  Mgm  →  ( ( 𝑠  ∈  ( Base ‘ 𝐺 )  ∧  𝑡  ∈  ( Base ‘ 𝐺 ) )  →  ( 𝑠 ( +g ‘ 𝐺 ) 𝑡 )  ∈  ( Base ‘ 𝐺 ) ) ) | 
						
							| 13 | 5 12 | syl | ⊢ ( 𝜑  →  ( ( 𝑠  ∈  ( Base ‘ 𝐺 )  ∧  𝑡  ∈  ( Base ‘ 𝐺 ) )  →  ( 𝑠 ( +g ‘ 𝐺 ) 𝑡 )  ∈  ( Base ‘ 𝐺 ) ) ) | 
						
							| 14 | 13 | imp | ⊢ ( ( 𝜑  ∧  ( 𝑠  ∈  ( Base ‘ 𝐺 )  ∧  𝑡  ∈  ( Base ‘ 𝐺 ) ) )  →  ( 𝑠 ( +g ‘ 𝐺 ) 𝑡 )  ∈  ( Base ‘ 𝐺 ) ) | 
						
							| 15 | 1 2 3 4 14 6 7 8 | gsumpropd2 | ⊢ ( 𝜑  →  ( 𝐺  Σg  𝐹 )  =  ( 𝐻  Σg  𝐹 ) ) |