| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ismot.p | ⊢ 𝑃  =  ( Base ‘ 𝐺 ) | 
						
							| 2 |  | ismot.m | ⊢  −   =  ( dist ‘ 𝐺 ) | 
						
							| 3 |  | motgrp.1 | ⊢ ( 𝜑  →  𝐺  ∈  𝑉 ) | 
						
							| 4 |  | motgrp.i | ⊢ 𝐼  =  { 〈 ( Base ‘ ndx ) ,  ( 𝐺 Ismt 𝐺 ) 〉 ,  〈 ( +g ‘ ndx ) ,  ( 𝑓  ∈  ( 𝐺 Ismt 𝐺 ) ,  𝑔  ∈  ( 𝐺 Ismt 𝐺 )  ↦  ( 𝑓  ∘  𝑔 ) ) 〉 } | 
						
							| 5 |  | motplusg.1 | ⊢ ( 𝜑  →  𝐹  ∈  ( 𝐺 Ismt 𝐺 ) ) | 
						
							| 6 |  | motplusg.2 | ⊢ ( 𝜑  →  𝐻  ∈  ( 𝐺 Ismt 𝐺 ) ) | 
						
							| 7 |  | coexg | ⊢ ( ( 𝐹  ∈  ( 𝐺 Ismt 𝐺 )  ∧  𝐻  ∈  ( 𝐺 Ismt 𝐺 ) )  →  ( 𝐹  ∘  𝐻 )  ∈  V ) | 
						
							| 8 | 5 6 7 | syl2anc | ⊢ ( 𝜑  →  ( 𝐹  ∘  𝐻 )  ∈  V ) | 
						
							| 9 |  | coeq1 | ⊢ ( 𝑎  =  𝐹  →  ( 𝑎  ∘  𝑏 )  =  ( 𝐹  ∘  𝑏 ) ) | 
						
							| 10 |  | coeq2 | ⊢ ( 𝑏  =  𝐻  →  ( 𝐹  ∘  𝑏 )  =  ( 𝐹  ∘  𝐻 ) ) | 
						
							| 11 |  | ovex | ⊢ ( 𝐺 Ismt 𝐺 )  ∈  V | 
						
							| 12 | 11 11 | mpoex | ⊢ ( 𝑓  ∈  ( 𝐺 Ismt 𝐺 ) ,  𝑔  ∈  ( 𝐺 Ismt 𝐺 )  ↦  ( 𝑓  ∘  𝑔 ) )  ∈  V | 
						
							| 13 | 4 | grpplusg | ⊢ ( ( 𝑓  ∈  ( 𝐺 Ismt 𝐺 ) ,  𝑔  ∈  ( 𝐺 Ismt 𝐺 )  ↦  ( 𝑓  ∘  𝑔 ) )  ∈  V  →  ( 𝑓  ∈  ( 𝐺 Ismt 𝐺 ) ,  𝑔  ∈  ( 𝐺 Ismt 𝐺 )  ↦  ( 𝑓  ∘  𝑔 ) )  =  ( +g ‘ 𝐼 ) ) | 
						
							| 14 | 12 13 | ax-mp | ⊢ ( 𝑓  ∈  ( 𝐺 Ismt 𝐺 ) ,  𝑔  ∈  ( 𝐺 Ismt 𝐺 )  ↦  ( 𝑓  ∘  𝑔 ) )  =  ( +g ‘ 𝐼 ) | 
						
							| 15 |  | coeq1 | ⊢ ( 𝑓  =  𝑎  →  ( 𝑓  ∘  𝑔 )  =  ( 𝑎  ∘  𝑔 ) ) | 
						
							| 16 |  | coeq2 | ⊢ ( 𝑔  =  𝑏  →  ( 𝑎  ∘  𝑔 )  =  ( 𝑎  ∘  𝑏 ) ) | 
						
							| 17 | 15 16 | cbvmpov | ⊢ ( 𝑓  ∈  ( 𝐺 Ismt 𝐺 ) ,  𝑔  ∈  ( 𝐺 Ismt 𝐺 )  ↦  ( 𝑓  ∘  𝑔 ) )  =  ( 𝑎  ∈  ( 𝐺 Ismt 𝐺 ) ,  𝑏  ∈  ( 𝐺 Ismt 𝐺 )  ↦  ( 𝑎  ∘  𝑏 ) ) | 
						
							| 18 | 14 17 | eqtr3i | ⊢ ( +g ‘ 𝐼 )  =  ( 𝑎  ∈  ( 𝐺 Ismt 𝐺 ) ,  𝑏  ∈  ( 𝐺 Ismt 𝐺 )  ↦  ( 𝑎  ∘  𝑏 ) ) | 
						
							| 19 | 9 10 18 | ovmpog | ⊢ ( ( 𝐹  ∈  ( 𝐺 Ismt 𝐺 )  ∧  𝐻  ∈  ( 𝐺 Ismt 𝐺 )  ∧  ( 𝐹  ∘  𝐻 )  ∈  V )  →  ( 𝐹 ( +g ‘ 𝐼 ) 𝐻 )  =  ( 𝐹  ∘  𝐻 ) ) | 
						
							| 20 | 5 6 8 19 | syl3anc | ⊢ ( 𝜑  →  ( 𝐹 ( +g ‘ 𝐼 ) 𝐻 )  =  ( 𝐹  ∘  𝐻 ) ) |