| Step | Hyp | Ref | Expression | 
						
							| 1 |  | issgrpd.b | ⊢ ( 𝜑  →  𝐵  =  ( Base ‘ 𝐺 ) ) | 
						
							| 2 |  | issgrpd.p | ⊢ ( 𝜑  →   +   =  ( +g ‘ 𝐺 ) ) | 
						
							| 3 |  | issgrpd.c | ⊢ ( ( 𝜑  ∧  𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  →  ( 𝑥  +  𝑦 )  ∈  𝐵 ) | 
						
							| 4 |  | issgrpd.a | ⊢ ( ( 𝜑  ∧  ( 𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵  ∧  𝑧  ∈  𝐵 ) )  →  ( ( 𝑥  +  𝑦 )  +  𝑧 )  =  ( 𝑥  +  ( 𝑦  +  𝑧 ) ) ) | 
						
							| 5 |  | issgrpd.v | ⊢ ( 𝜑  →  𝐺  ∈  𝑉 ) | 
						
							| 6 | 3 | 3expib | ⊢ ( 𝜑  →  ( ( 𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  →  ( 𝑥  +  𝑦 )  ∈  𝐵 ) ) | 
						
							| 7 | 1 | eleq2d | ⊢ ( 𝜑  →  ( 𝑥  ∈  𝐵  ↔  𝑥  ∈  ( Base ‘ 𝐺 ) ) ) | 
						
							| 8 | 1 | eleq2d | ⊢ ( 𝜑  →  ( 𝑦  ∈  𝐵  ↔  𝑦  ∈  ( Base ‘ 𝐺 ) ) ) | 
						
							| 9 | 7 8 | anbi12d | ⊢ ( 𝜑  →  ( ( 𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  ↔  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  𝑦  ∈  ( Base ‘ 𝐺 ) ) ) ) | 
						
							| 10 | 2 | oveqd | ⊢ ( 𝜑  →  ( 𝑥  +  𝑦 )  =  ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ) | 
						
							| 11 | 10 1 | eleq12d | ⊢ ( 𝜑  →  ( ( 𝑥  +  𝑦 )  ∈  𝐵  ↔  ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  ∈  ( Base ‘ 𝐺 ) ) ) | 
						
							| 12 | 6 9 11 | 3imtr3d | ⊢ ( 𝜑  →  ( ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  𝑦  ∈  ( Base ‘ 𝐺 ) )  →  ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  ∈  ( Base ‘ 𝐺 ) ) ) | 
						
							| 13 | 12 | imp | ⊢ ( ( 𝜑  ∧  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  𝑦  ∈  ( Base ‘ 𝐺 ) ) )  →  ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  ∈  ( Base ‘ 𝐺 ) ) | 
						
							| 14 |  | df-3an | ⊢ ( ( 𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵  ∧  𝑧  ∈  𝐵 )  ↔  ( ( 𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  ∧  𝑧  ∈  𝐵 ) ) | 
						
							| 15 | 14 4 | sylan2br | ⊢ ( ( 𝜑  ∧  ( ( 𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  ∧  𝑧  ∈  𝐵 ) )  →  ( ( 𝑥  +  𝑦 )  +  𝑧 )  =  ( 𝑥  +  ( 𝑦  +  𝑧 ) ) ) | 
						
							| 16 | 15 | ex | ⊢ ( 𝜑  →  ( ( ( 𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  ∧  𝑧  ∈  𝐵 )  →  ( ( 𝑥  +  𝑦 )  +  𝑧 )  =  ( 𝑥  +  ( 𝑦  +  𝑧 ) ) ) ) | 
						
							| 17 | 1 | eleq2d | ⊢ ( 𝜑  →  ( 𝑧  ∈  𝐵  ↔  𝑧  ∈  ( Base ‘ 𝐺 ) ) ) | 
						
							| 18 | 9 17 | anbi12d | ⊢ ( 𝜑  →  ( ( ( 𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  ∧  𝑧  ∈  𝐵 )  ↔  ( ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  𝑦  ∈  ( Base ‘ 𝐺 ) )  ∧  𝑧  ∈  ( Base ‘ 𝐺 ) ) ) ) | 
						
							| 19 |  | eqidd | ⊢ ( 𝜑  →  𝑧  =  𝑧 ) | 
						
							| 20 | 2 10 19 | oveq123d | ⊢ ( 𝜑  →  ( ( 𝑥  +  𝑦 )  +  𝑧 )  =  ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ( +g ‘ 𝐺 ) 𝑧 ) ) | 
						
							| 21 |  | eqidd | ⊢ ( 𝜑  →  𝑥  =  𝑥 ) | 
						
							| 22 | 2 | oveqd | ⊢ ( 𝜑  →  ( 𝑦  +  𝑧 )  =  ( 𝑦 ( +g ‘ 𝐺 ) 𝑧 ) ) | 
						
							| 23 | 2 21 22 | oveq123d | ⊢ ( 𝜑  →  ( 𝑥  +  ( 𝑦  +  𝑧 ) )  =  ( 𝑥 ( +g ‘ 𝐺 ) ( 𝑦 ( +g ‘ 𝐺 ) 𝑧 ) ) ) | 
						
							| 24 | 20 23 | eqeq12d | ⊢ ( 𝜑  →  ( ( ( 𝑥  +  𝑦 )  +  𝑧 )  =  ( 𝑥  +  ( 𝑦  +  𝑧 ) )  ↔  ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ( +g ‘ 𝐺 ) 𝑧 )  =  ( 𝑥 ( +g ‘ 𝐺 ) ( 𝑦 ( +g ‘ 𝐺 ) 𝑧 ) ) ) ) | 
						
							| 25 | 16 18 24 | 3imtr3d | ⊢ ( 𝜑  →  ( ( ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  𝑦  ∈  ( Base ‘ 𝐺 ) )  ∧  𝑧  ∈  ( Base ‘ 𝐺 ) )  →  ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ( +g ‘ 𝐺 ) 𝑧 )  =  ( 𝑥 ( +g ‘ 𝐺 ) ( 𝑦 ( +g ‘ 𝐺 ) 𝑧 ) ) ) ) | 
						
							| 26 | 25 | impl | ⊢ ( ( ( 𝜑  ∧  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  𝑦  ∈  ( Base ‘ 𝐺 ) ) )  ∧  𝑧  ∈  ( Base ‘ 𝐺 ) )  →  ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ( +g ‘ 𝐺 ) 𝑧 )  =  ( 𝑥 ( +g ‘ 𝐺 ) ( 𝑦 ( +g ‘ 𝐺 ) 𝑧 ) ) ) | 
						
							| 27 | 26 | ralrimiva | ⊢ ( ( 𝜑  ∧  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  𝑦  ∈  ( Base ‘ 𝐺 ) ) )  →  ∀ 𝑧  ∈  ( Base ‘ 𝐺 ) ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ( +g ‘ 𝐺 ) 𝑧 )  =  ( 𝑥 ( +g ‘ 𝐺 ) ( 𝑦 ( +g ‘ 𝐺 ) 𝑧 ) ) ) | 
						
							| 28 | 13 27 | jca | ⊢ ( ( 𝜑  ∧  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  𝑦  ∈  ( Base ‘ 𝐺 ) ) )  →  ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑧  ∈  ( Base ‘ 𝐺 ) ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ( +g ‘ 𝐺 ) 𝑧 )  =  ( 𝑥 ( +g ‘ 𝐺 ) ( 𝑦 ( +g ‘ 𝐺 ) 𝑧 ) ) ) ) | 
						
							| 29 | 28 | ralrimivva | ⊢ ( 𝜑  →  ∀ 𝑥  ∈  ( Base ‘ 𝐺 ) ∀ 𝑦  ∈  ( Base ‘ 𝐺 ) ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑧  ∈  ( Base ‘ 𝐺 ) ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ( +g ‘ 𝐺 ) 𝑧 )  =  ( 𝑥 ( +g ‘ 𝐺 ) ( 𝑦 ( +g ‘ 𝐺 ) 𝑧 ) ) ) ) | 
						
							| 30 |  | eqid | ⊢ ( Base ‘ 𝐺 )  =  ( Base ‘ 𝐺 ) | 
						
							| 31 |  | eqid | ⊢ ( +g ‘ 𝐺 )  =  ( +g ‘ 𝐺 ) | 
						
							| 32 | 30 31 | issgrpv | ⊢ ( 𝐺  ∈  𝑉  →  ( 𝐺  ∈  Smgrp  ↔  ∀ 𝑥  ∈  ( Base ‘ 𝐺 ) ∀ 𝑦  ∈  ( Base ‘ 𝐺 ) ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑧  ∈  ( Base ‘ 𝐺 ) ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ( +g ‘ 𝐺 ) 𝑧 )  =  ( 𝑥 ( +g ‘ 𝐺 ) ( 𝑦 ( +g ‘ 𝐺 ) 𝑧 ) ) ) ) ) | 
						
							| 33 | 5 32 | syl | ⊢ ( 𝜑  →  ( 𝐺  ∈  Smgrp  ↔  ∀ 𝑥  ∈  ( Base ‘ 𝐺 ) ∀ 𝑦  ∈  ( Base ‘ 𝐺 ) ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑧  ∈  ( Base ‘ 𝐺 ) ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ( +g ‘ 𝐺 ) 𝑧 )  =  ( 𝑥 ( +g ‘ 𝐺 ) ( 𝑦 ( +g ‘ 𝐺 ) 𝑧 ) ) ) ) ) | 
						
							| 34 | 29 33 | mpbird | ⊢ ( 𝜑  →  𝐺  ∈  Smgrp ) |