| Step | Hyp | Ref | Expression | 
						
							| 1 |  | idn1 | ⊢ (    ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )    ▶    ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )    ) | 
						
							| 2 |  | df-3an | ⊢ ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  ↔  ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 ) ) | 
						
							| 3 |  | imbi1 | ⊢ ( ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  ↔  ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 ) )  →  ( ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )  ↔  ( ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 )  →  𝜃 ) ) ) | 
						
							| 4 | 3 | biimpcd | ⊢ ( ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )  →  ( ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  ↔  ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 ) )  →  ( ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 )  →  𝜃 ) ) ) | 
						
							| 5 | 1 2 4 | e10 | ⊢ (    ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )    ▶    ( ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 )  →  𝜃 )    ) | 
						
							| 6 |  | pm3.3 | ⊢ ( ( ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 )  →  𝜃 )  →  ( ( 𝜑  ∧  𝜓 )  →  ( 𝜒  →  𝜃 ) ) ) | 
						
							| 7 | 5 6 | e1a | ⊢ (    ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )    ▶    ( ( 𝜑  ∧  𝜓 )  →  ( 𝜒  →  𝜃 ) )    ) | 
						
							| 8 |  | pm3.3 | ⊢ ( ( ( 𝜑  ∧  𝜓 )  →  ( 𝜒  →  𝜃 ) )  →  ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) ) ) | 
						
							| 9 | 7 8 | e1a | ⊢ (    ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )    ▶    ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) )    ) | 
						
							| 10 | 9 | in1 | ⊢ ( ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )  →  ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) ) ) | 
						
							| 11 |  | idn1 | ⊢ (    ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) )    ▶    ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) )    ) | 
						
							| 12 |  | pm3.31 | ⊢ ( ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) )  →  ( ( 𝜑  ∧  𝜓 )  →  ( 𝜒  →  𝜃 ) ) ) | 
						
							| 13 | 11 12 | e1a | ⊢ (    ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) )    ▶    ( ( 𝜑  ∧  𝜓 )  →  ( 𝜒  →  𝜃 ) )    ) | 
						
							| 14 |  | pm3.31 | ⊢ ( ( ( 𝜑  ∧  𝜓 )  →  ( 𝜒  →  𝜃 ) )  →  ( ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 )  →  𝜃 ) ) | 
						
							| 15 | 13 14 | e1a | ⊢ (    ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) )    ▶    ( ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 )  →  𝜃 )    ) | 
						
							| 16 | 3 | biimprd | ⊢ ( ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  ↔  ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 ) )  →  ( ( ( ( 𝜑  ∧  𝜓 )  ∧  𝜒 )  →  𝜃 )  →  ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 ) ) ) | 
						
							| 17 | 2 15 16 | e01 | ⊢ (    ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) )    ▶    ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )    ) | 
						
							| 18 | 17 | in1 | ⊢ ( ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) )  →  ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 ) ) | 
						
							| 19 |  | impbi | ⊢ ( ( ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )  →  ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) ) )  →  ( ( ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) )  →  ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 ) )  →  ( ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )  ↔  ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) ) ) ) ) | 
						
							| 20 | 10 18 19 | e00 | ⊢ ( ( ( 𝜑  ∧  𝜓  ∧  𝜒 )  →  𝜃 )  ↔  ( 𝜑  →  ( 𝜓  →  ( 𝜒  →  𝜃 ) ) ) ) |