| Step | Hyp | Ref | Expression | 
						
							| 1 |  | pm1.4 | ⊢ ( ( 𝜑  ∨  𝜒 )  →  ( 𝜒  ∨  𝜑 ) ) | 
						
							| 2 | 1 | ord | ⊢ ( ( 𝜑  ∨  𝜒 )  →  ( ¬  𝜒  →  𝜑 ) ) | 
						
							| 3 |  | pm4.83 | ⊢ ( ( ( 𝜒  →  𝜑 )  ∧  ( ¬  𝜒  →  𝜑 ) )  ↔  𝜑 ) | 
						
							| 4 | 3 | biimpi | ⊢ ( ( ( 𝜒  →  𝜑 )  ∧  ( ¬  𝜒  →  𝜑 ) )  →  𝜑 ) | 
						
							| 5 | 2 4 | sylan2 | ⊢ ( ( ( 𝜒  →  𝜑 )  ∧  ( 𝜑  ∨  𝜒 ) )  →  𝜑 ) | 
						
							| 6 | 5 | ex | ⊢ ( ( 𝜒  →  𝜑 )  →  ( ( 𝜑  ∨  𝜒 )  →  𝜑 ) ) | 
						
							| 7 | 6 | anim1d | ⊢ ( ( 𝜒  →  𝜑 )  →  ( ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) )  →  ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) ) ) ) | 
						
							| 8 |  | orc | ⊢ ( 𝜑  →  ( 𝜑  ∨  𝜒 ) ) | 
						
							| 9 | 8 | anim1i | ⊢ ( ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) )  →  ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) ) ) | 
						
							| 10 | 7 9 | jctir | ⊢ ( ( 𝜒  →  𝜑 )  →  ( ( ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) )  →  ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) ) )  ∧  ( ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) )  →  ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) ) ) ) ) | 
						
							| 11 |  | olc | ⊢ ( 𝜒  →  ( 𝜑  ∨  𝜒 ) ) | 
						
							| 12 |  | olc | ⊢ ( 𝜒  →  ( 𝜓  ∨  𝜒 ) ) | 
						
							| 13 | 11 12 | jca | ⊢ ( 𝜒  →  ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) ) ) | 
						
							| 14 |  | simpl | ⊢ ( ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) )  →  𝜑 ) | 
						
							| 15 | 13 14 | imim12i | ⊢ ( ( ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) )  →  ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) ) )  →  ( 𝜒  →  𝜑 ) ) | 
						
							| 16 | 15 | adantr | ⊢ ( ( ( ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) )  →  ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) ) )  ∧  ( ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) )  →  ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) ) ) )  →  ( 𝜒  →  𝜑 ) ) | 
						
							| 17 | 10 16 | impbii | ⊢ ( ( 𝜒  →  𝜑 )  ↔  ( ( ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) )  →  ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) ) )  ∧  ( ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) )  →  ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) ) ) ) ) | 
						
							| 18 |  | dfbi2 | ⊢ ( ( ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) )  ↔  ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) ) )  ↔  ( ( ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) )  →  ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) ) )  ∧  ( ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) )  →  ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) ) ) ) ) | 
						
							| 19 |  | ordir | ⊢ ( ( ( 𝜑  ∧  𝜓 )  ∨  𝜒 )  ↔  ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) ) ) | 
						
							| 20 | 19 | bicomi | ⊢ ( ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) )  ↔  ( ( 𝜑  ∧  𝜓 )  ∨  𝜒 ) ) | 
						
							| 21 | 20 | bibi1i | ⊢ ( ( ( ( 𝜑  ∨  𝜒 )  ∧  ( 𝜓  ∨  𝜒 ) )  ↔  ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) ) )  ↔  ( ( ( 𝜑  ∧  𝜓 )  ∨  𝜒 )  ↔  ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) ) ) ) | 
						
							| 22 | 17 18 21 | 3bitr2i | ⊢ ( ( 𝜒  →  𝜑 )  ↔  ( ( ( 𝜑  ∧  𝜓 )  ∨  𝜒 )  ↔  ( 𝜑  ∧  ( 𝜓  ∨  𝜒 ) ) ) ) |