| Step | Hyp | Ref | Expression | 
						
							| 1 |  | prdsgrpd.y | ⊢ 𝑌  =  ( 𝑆 Xs 𝑅 ) | 
						
							| 2 |  | prdsgrpd.i | ⊢ ( 𝜑  →  𝐼  ∈  𝑊 ) | 
						
							| 3 |  | prdsgrpd.s | ⊢ ( 𝜑  →  𝑆  ∈  𝑉 ) | 
						
							| 4 |  | prdsgrpd.r | ⊢ ( 𝜑  →  𝑅 : 𝐼 ⟶ Grp ) | 
						
							| 5 |  | prdsinvgd.b | ⊢ 𝐵  =  ( Base ‘ 𝑌 ) | 
						
							| 6 |  | prdsinvgd.n | ⊢ 𝑁  =  ( invg ‘ 𝑌 ) | 
						
							| 7 |  | prdsinvgd.x | ⊢ ( 𝜑  →  𝑋  ∈  𝐵 ) | 
						
							| 8 |  | eqid | ⊢ ( +g ‘ 𝑌 )  =  ( +g ‘ 𝑌 ) | 
						
							| 9 | 3 | elexd | ⊢ ( 𝜑  →  𝑆  ∈  V ) | 
						
							| 10 | 2 | elexd | ⊢ ( 𝜑  →  𝐼  ∈  V ) | 
						
							| 11 |  | eqid | ⊢ ( 0g  ∘  𝑅 )  =  ( 0g  ∘  𝑅 ) | 
						
							| 12 |  | eqid | ⊢ ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) )  =  ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) ) | 
						
							| 13 | 1 5 8 9 10 4 7 11 12 | prdsinvlem | ⊢ ( 𝜑  →  ( ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) )  ∈  𝐵  ∧  ( ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) ) ( +g ‘ 𝑌 ) 𝑋 )  =  ( 0g  ∘  𝑅 ) ) ) | 
						
							| 14 | 13 | simprd | ⊢ ( 𝜑  →  ( ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) ) ( +g ‘ 𝑌 ) 𝑋 )  =  ( 0g  ∘  𝑅 ) ) | 
						
							| 15 |  | grpmnd | ⊢ ( 𝑎  ∈  Grp  →  𝑎  ∈  Mnd ) | 
						
							| 16 | 15 | ssriv | ⊢ Grp  ⊆  Mnd | 
						
							| 17 |  | fss | ⊢ ( ( 𝑅 : 𝐼 ⟶ Grp  ∧  Grp  ⊆  Mnd )  →  𝑅 : 𝐼 ⟶ Mnd ) | 
						
							| 18 | 4 16 17 | sylancl | ⊢ ( 𝜑  →  𝑅 : 𝐼 ⟶ Mnd ) | 
						
							| 19 | 1 2 3 18 | prds0g | ⊢ ( 𝜑  →  ( 0g  ∘  𝑅 )  =  ( 0g ‘ 𝑌 ) ) | 
						
							| 20 | 14 19 | eqtrd | ⊢ ( 𝜑  →  ( ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) ) ( +g ‘ 𝑌 ) 𝑋 )  =  ( 0g ‘ 𝑌 ) ) | 
						
							| 21 | 1 2 3 4 | prdsgrpd | ⊢ ( 𝜑  →  𝑌  ∈  Grp ) | 
						
							| 22 | 13 | simpld | ⊢ ( 𝜑  →  ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) )  ∈  𝐵 ) | 
						
							| 23 |  | eqid | ⊢ ( 0g ‘ 𝑌 )  =  ( 0g ‘ 𝑌 ) | 
						
							| 24 | 5 8 23 6 | grpinvid2 | ⊢ ( ( 𝑌  ∈  Grp  ∧  𝑋  ∈  𝐵  ∧  ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) )  ∈  𝐵 )  →  ( ( 𝑁 ‘ 𝑋 )  =  ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) )  ↔  ( ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) ) ( +g ‘ 𝑌 ) 𝑋 )  =  ( 0g ‘ 𝑌 ) ) ) | 
						
							| 25 | 21 7 22 24 | syl3anc | ⊢ ( 𝜑  →  ( ( 𝑁 ‘ 𝑋 )  =  ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) )  ↔  ( ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) ) ( +g ‘ 𝑌 ) 𝑋 )  =  ( 0g ‘ 𝑌 ) ) ) | 
						
							| 26 | 20 25 | mpbird | ⊢ ( 𝜑  →  ( 𝑁 ‘ 𝑋 )  =  ( 𝑥  ∈  𝐼  ↦  ( ( invg ‘ ( 𝑅 ‘ 𝑥 ) ) ‘ ( 𝑋 ‘ 𝑥 ) ) ) ) |