| Step | Hyp | Ref | Expression | 
						
							| 1 |  | axacnd | ⊢ ∃ 𝑥 ∀ 𝑦 ∀ 𝑧 ( ∀ 𝑥 ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  →  ∃ 𝑤 ∀ 𝑦 ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  𝑦  =  𝑤 ) ) | 
						
							| 2 |  | df-an | ⊢ ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ↔  ¬  ( 𝑦  ∈  𝑧  →  ¬  𝑧  ∈  𝑤 ) ) | 
						
							| 3 | 2 | albii | ⊢ ( ∀ 𝑥 ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ↔  ∀ 𝑥 ¬  ( 𝑦  ∈  𝑧  →  ¬  𝑧  ∈  𝑤 ) ) | 
						
							| 4 |  | anass | ⊢ ( ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  ( 𝑦  ∈  𝑧  ∧  ( 𝑧  ∈  𝑤  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) ) ) ) | 
						
							| 5 |  | annim | ⊢ ( ( 𝑧  ∈  𝑤  ∧  ¬  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) )  ↔  ¬  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) | 
						
							| 6 |  | pm4.63 | ⊢ ( ¬  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 )  ↔  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) ) | 
						
							| 7 | 6 | anbi2i | ⊢ ( ( 𝑧  ∈  𝑤  ∧  ¬  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) )  ↔  ( 𝑧  ∈  𝑤  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) ) ) | 
						
							| 8 | 5 7 | bitr3i | ⊢ ( ¬  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) )  ↔  ( 𝑧  ∈  𝑤  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) ) ) | 
						
							| 9 | 8 | anbi2i | ⊢ ( ( 𝑦  ∈  𝑧  ∧  ¬  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  ↔  ( 𝑦  ∈  𝑧  ∧  ( 𝑧  ∈  𝑤  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) ) ) ) | 
						
							| 10 |  | annim | ⊢ ( ( 𝑦  ∈  𝑧  ∧  ¬  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  ↔  ¬  ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) | 
						
							| 11 | 4 9 10 | 3bitr2i | ⊢ ( ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  ¬  ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) | 
						
							| 12 | 11 | exbii | ⊢ ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  ∃ 𝑤 ¬  ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) | 
						
							| 13 |  | exnal | ⊢ ( ∃ 𝑤 ¬  ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  ↔  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) | 
						
							| 14 | 12 13 | bitri | ⊢ ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) | 
						
							| 15 | 14 | bibi1i | ⊢ ( ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  𝑦  =  𝑤 )  ↔  ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  ↔  𝑦  =  𝑤 ) ) | 
						
							| 16 |  | dfbi1 | ⊢ ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  ↔  𝑦  =  𝑤 )  ↔  ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) | 
						
							| 17 | 15 16 | bitri | ⊢ ( ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  𝑦  =  𝑤 )  ↔  ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) | 
						
							| 18 | 17 | albii | ⊢ ( ∀ 𝑦 ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  𝑦  =  𝑤 )  ↔  ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) | 
						
							| 19 | 18 | exbii | ⊢ ( ∃ 𝑤 ∀ 𝑦 ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  𝑦  =  𝑤 )  ↔  ∃ 𝑤 ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) | 
						
							| 20 |  | df-ex | ⊢ ( ∃ 𝑤 ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) )  ↔  ¬  ∀ 𝑤 ¬  ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) | 
						
							| 21 | 19 20 | bitri | ⊢ ( ∃ 𝑤 ∀ 𝑦 ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  𝑦  =  𝑤 )  ↔  ¬  ∀ 𝑤 ¬  ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) | 
						
							| 22 | 3 21 | imbi12i | ⊢ ( ( ∀ 𝑥 ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  →  ∃ 𝑤 ∀ 𝑦 ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  𝑦  =  𝑤 ) )  ↔  ( ∀ 𝑥 ¬  ( 𝑦  ∈  𝑧  →  ¬  𝑧  ∈  𝑤 )  →  ¬  ∀ 𝑤 ¬  ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) ) | 
						
							| 23 | 22 | 2albii | ⊢ ( ∀ 𝑦 ∀ 𝑧 ( ∀ 𝑥 ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  →  ∃ 𝑤 ∀ 𝑦 ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  𝑦  =  𝑤 ) )  ↔  ∀ 𝑦 ∀ 𝑧 ( ∀ 𝑥 ¬  ( 𝑦  ∈  𝑧  →  ¬  𝑧  ∈  𝑤 )  →  ¬  ∀ 𝑤 ¬  ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) ) | 
						
							| 24 | 23 | exbii | ⊢ ( ∃ 𝑥 ∀ 𝑦 ∀ 𝑧 ( ∀ 𝑥 ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  →  ∃ 𝑤 ∀ 𝑦 ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  𝑦  =  𝑤 ) )  ↔  ∃ 𝑥 ∀ 𝑦 ∀ 𝑧 ( ∀ 𝑥 ¬  ( 𝑦  ∈  𝑧  →  ¬  𝑧  ∈  𝑤 )  →  ¬  ∀ 𝑤 ¬  ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) ) | 
						
							| 25 |  | df-ex | ⊢ ( ∃ 𝑥 ∀ 𝑦 ∀ 𝑧 ( ∀ 𝑥 ¬  ( 𝑦  ∈  𝑧  →  ¬  𝑧  ∈  𝑤 )  →  ¬  ∀ 𝑤 ¬  ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) )  ↔  ¬  ∀ 𝑥 ¬  ∀ 𝑦 ∀ 𝑧 ( ∀ 𝑥 ¬  ( 𝑦  ∈  𝑧  →  ¬  𝑧  ∈  𝑤 )  →  ¬  ∀ 𝑤 ¬  ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) ) | 
						
							| 26 | 24 25 | bitri | ⊢ ( ∃ 𝑥 ∀ 𝑦 ∀ 𝑧 ( ∀ 𝑥 ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  →  ∃ 𝑤 ∀ 𝑦 ( ∃ 𝑤 ( ( 𝑦  ∈  𝑧  ∧  𝑧  ∈  𝑤 )  ∧  ( 𝑦  ∈  𝑤  ∧  𝑤  ∈  𝑥 ) )  ↔  𝑦  =  𝑤 ) )  ↔  ¬  ∀ 𝑥 ¬  ∀ 𝑦 ∀ 𝑧 ( ∀ 𝑥 ¬  ( 𝑦  ∈  𝑧  →  ¬  𝑧  ∈  𝑤 )  →  ¬  ∀ 𝑤 ¬  ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) ) | 
						
							| 27 | 1 26 | mpbi | ⊢ ¬  ∀ 𝑥 ¬  ∀ 𝑦 ∀ 𝑧 ( ∀ 𝑥 ¬  ( 𝑦  ∈  𝑧  →  ¬  𝑧  ∈  𝑤 )  →  ¬  ∀ 𝑤 ¬  ∀ 𝑦 ¬  ( ( ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) )  →  𝑦  =  𝑤 )  →  ¬  ( 𝑦  =  𝑤  →  ¬  ∀ 𝑤 ( 𝑦  ∈  𝑧  →  ( 𝑧  ∈  𝑤  →  ( 𝑦  ∈  𝑤  →  ¬  𝑤  ∈  𝑥 ) ) ) ) ) ) |