| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ac6s6.1 | ⊢ Ⅎ 𝑦 𝜓 | 
						
							| 2 |  | ac6s6.2 | ⊢ 𝐴  ∈  V | 
						
							| 3 |  | ac6s6.3 | ⊢ ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) ) | 
						
							| 4 |  | hbe1 | ⊢ ( ∃ 𝑦 𝜑  →  ∀ 𝑦 ∃ 𝑦 𝜑 ) | 
						
							| 5 |  | iftrue | ⊢ ( ∃ 𝑦 𝜑  →  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  =  { 𝑦  ∣  𝜑 } ) | 
						
							| 6 | 5 | eqabrd | ⊢ ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) ) | 
						
							| 7 | 4 6 | exbidh | ⊢ ( ∃ 𝑦 𝜑  →  ( ∃ 𝑦 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ∃ 𝑦 𝜑 ) ) | 
						
							| 8 | 7 | ibir | ⊢ ( ∃ 𝑦 𝜑  →  ∃ 𝑦 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V ) ) | 
						
							| 9 |  | vex | ⊢ 𝑦  ∈  V | 
						
							| 10 | 9 | exgen | ⊢ ∃ 𝑦 𝑦  ∈  V | 
						
							| 11 | 4 | hbn | ⊢ ( ¬  ∃ 𝑦 𝜑  →  ∀ 𝑦 ¬  ∃ 𝑦 𝜑 ) | 
						
							| 12 |  | iffalse | ⊢ ( ¬  ∃ 𝑦 𝜑  →  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  =  V ) | 
						
							| 13 | 12 | eleq2d | ⊢ ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) ) | 
						
							| 14 | 11 13 | exbidh | ⊢ ( ¬  ∃ 𝑦 𝜑  →  ( ∃ 𝑦 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ∃ 𝑦 𝑦  ∈  V ) ) | 
						
							| 15 | 10 14 | mpbiri | ⊢ ( ¬  ∃ 𝑦 𝜑  →  ∃ 𝑦 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V ) ) | 
						
							| 16 | 8 15 | pm2.61i | ⊢ ∃ 𝑦 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V ) | 
						
							| 17 | 16 | rgenw | ⊢ ∀ 𝑥  ∈  𝐴 ∃ 𝑦 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V ) | 
						
							| 18 |  | nfe1 | ⊢ Ⅎ 𝑦 ∃ 𝑦 𝜑 | 
						
							| 19 | 18 1 | nfim | ⊢ Ⅎ 𝑦 ( ∃ 𝑦 𝜑  →  𝜓 ) | 
						
							| 20 |  | id | ⊢ ( ¬  𝜑  →  ¬  𝜑 ) | 
						
							| 21 | 20 | a1i | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ¬  𝜑 ) ) | 
						
							| 22 |  | ax-1 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) ) | 
						
							| 23 |  | tsim3 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  ∨  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) ) | 
						
							| 24 | 23 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ¬  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  ∨  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) ) ) | 
						
							| 25 | 22 24 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ¬  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 26 |  | tsim3 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) )  ∨  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 27 | 26 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ¬  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) )  ∨  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) ) | 
						
							| 28 | 25 27 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ¬  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 29 |  | tsim2 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ∃ 𝑦 𝜑  ∨  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 30 | 29 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ∃ 𝑦 𝜑  ∨  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 31 | 28 30 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ∃ 𝑦 𝜑 ) ) | 
						
							| 32 |  | tsim2 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  ∨  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 33 | 32 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  ∨  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) ) | 
						
							| 34 | 25 33 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) ) ) ) | 
						
							| 35 | 31 34 | mpdd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) ) ) | 
						
							| 36 |  | tsbi4 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  𝜑 )  ∨  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) ) ) | 
						
							| 37 | 36 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  𝜑 )  ∨  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) ) ) ) | 
						
							| 38 | 35 37 | cnfn2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  𝜑 ) ) ) | 
						
							| 39 | 21 38 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V ) ) ) | 
						
							| 40 |  | tsim3 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) )  ∨  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 41 | 40 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ¬  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) )  ∨  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 42 | 28 41 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ¬  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 43 |  | tsim3 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 44 | 43 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 45 | 42 44 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 46 |  | tsbi2 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 47 | 46 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 48 | 45 47 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 49 | 39 48 | cnf1dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) | 
						
							| 50 |  | tsim2 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  ∨  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 51 | 50 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  ∨  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 52 | 42 51 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  𝑦  =  ( 𝑓 ‘ 𝑥 ) ) ) | 
						
							| 53 |  | simplim | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) ) ) | 
						
							| 54 | 52 53 | syld | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( 𝜑  ↔  𝜓 ) ) ) | 
						
							| 55 |  | tsbi3 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ( 𝜑  ∨  ¬  𝜓 )  ∨  ¬  ( 𝜑  ↔  𝜓 ) ) ) | 
						
							| 56 | 55 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ( 𝜑  ∨  ¬  𝜓 )  ∨  ¬  ( 𝜑  ↔  𝜓 ) ) ) ) | 
						
							| 57 | 54 56 | cnfn2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( 𝜑  ∨  ¬  𝜓 ) ) ) | 
						
							| 58 | 21 57 | cnf1dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ¬  𝜓 ) ) | 
						
							| 59 |  | tsim1 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ( ¬  ∃ 𝑦 𝜑  ∨  𝜓 )  ∨  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) | 
						
							| 60 | 59 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ( ¬  ∃ 𝑦 𝜑  ∨  𝜓 )  ∨  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 61 | 60 | or32dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ( ¬  ∃ 𝑦 𝜑  ∨  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  𝜓 ) ) ) | 
						
							| 62 | 58 61 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ( ¬  ∃ 𝑦 𝜑  ∨  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 63 | 31 62 | cnfn1dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  𝜑  →  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) | 
						
							| 64 | 49 63 | contrd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  𝜑 ) | 
						
							| 65 | 64 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  𝜑 ) ) | 
						
							| 66 |  | ax-1 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) ) | 
						
							| 67 | 23 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  ∨  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) ) ) | 
						
							| 68 | 66 67 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ¬  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 69 | 26 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) )  ∨  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) ) | 
						
							| 70 | 68 69 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ¬  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 71 | 29 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ∃ 𝑦 𝜑  ∨  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 72 | 70 71 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ∃ 𝑦 𝜑 ) ) | 
						
							| 73 | 32 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  ∨  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) ) | 
						
							| 74 | 68 73 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) ) ) ) | 
						
							| 75 | 72 74 | mpdd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) ) ) | 
						
							| 76 |  | tsbi3 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  𝜑 )  ∨  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) ) ) | 
						
							| 77 | 76 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  𝜑 )  ∨  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) ) ) ) | 
						
							| 78 | 75 77 | cnfn2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  𝜑 ) ) ) | 
						
							| 79 | 65 78 | cnfn2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V ) ) ) | 
						
							| 80 | 40 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) )  ∨  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 81 | 70 80 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ¬  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 82 | 50 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  ∨  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 83 | 81 82 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  𝑦  =  ( 𝑓 ‘ 𝑥 ) ) ) | 
						
							| 84 | 83 53 | syld | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( 𝜑  ↔  𝜓 ) ) ) | 
						
							| 85 |  | tsbi4 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ( ¬  𝜑  ∨  𝜓 )  ∨  ¬  ( 𝜑  ↔  𝜓 ) ) ) | 
						
							| 86 | 85 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ( ¬  𝜑  ∨  𝜓 )  ∨  ¬  ( 𝜑  ↔  𝜓 ) ) ) ) | 
						
							| 87 | 84 86 | cnfn2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  𝜑  ∨  𝜓 ) ) ) | 
						
							| 88 | 65 87 | cnfn1dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  𝜓 ) ) | 
						
							| 89 | 88 | a1dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) | 
						
							| 90 |  | tsbi1 | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 91 | 90 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 92 | 91 | or32dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) )  ∨  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 93 | 89 92 | cnfn2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 94 | 79 93 | cnfn1dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 95 | 43 | a1d | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 96 | 81 95 | cnf2dd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ( ¬  ⊥  →  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 97 | 94 96 | contrd | ⊢ ( ¬  ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) )  →  ⊥ ) | 
						
							| 98 | 97 | efald2 | ⊢ ( ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝜑  ↔  𝜓 ) )  →  ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 99 | 3 98 | ax-mp | ⊢ ( ( ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝜑 ) )  →  ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 100 | 6 99 | ax-mp | ⊢ ( ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 101 | 9 | a1i | ⊢ ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V ) | 
						
							| 102 |  | id | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) ) | 
						
							| 103 |  | tsim2 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ∃ 𝑦 𝜑  ∨  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) | 
						
							| 104 | 103 | ord | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ¬  ∃ 𝑦 𝜑  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) | 
						
							| 105 | 104 | a1dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ¬  ∃ 𝑦 𝜑  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) ) | 
						
							| 106 | 105 | a1dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ¬  ∃ 𝑦 𝜑  →  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) ) ) | 
						
							| 107 | 102 106 | mt3d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ¬  ∃ 𝑦 𝜑 ) | 
						
							| 108 | 107 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ⊥  →  ¬  ∃ 𝑦 𝜑 ) ) | 
						
							| 109 |  | simplim | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V ) ) | 
						
							| 110 | 108 109 | syld | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ⊥  →  𝑦  ∈  V ) ) | 
						
							| 111 |  | tsim2 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  ∨  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) ) | 
						
							| 112 | 111 | ord | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) ) | 
						
							| 113 | 112 | a1dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) ) ) | 
						
							| 114 | 102 113 | mt3d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) ) ) | 
						
							| 115 | 108 114 | syld | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ⊥  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) ) ) | 
						
							| 116 |  | id | ⊢ ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V ) ) | 
						
							| 117 | 116 | notornotel2 | ⊢ ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  𝑦  ∈  V ) | 
						
							| 118 | 117 | a1i | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  𝑦  ∈  V ) ) | 
						
							| 119 | 116 | notornotel1 | ⊢ ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) ) | 
						
							| 120 | 119 | a1i | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) ) ) | 
						
							| 121 |  | tsbi3 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  𝑦  ∈  V )  ∨  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) ) ) | 
						
							| 122 | 121 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ( ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  𝑦  ∈  V )  ∨  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) ) ) ) | 
						
							| 123 | 120 122 | cnfn2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  𝑦  ∈  V ) ) ) | 
						
							| 124 | 118 123 | cnfn2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V ) ) ) | 
						
							| 125 |  | trud | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ⊤ ) | 
						
							| 126 | 125 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ⊤ ) ) | 
						
							| 127 |  | tsbi1 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  ⊤ )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) | 
						
							| 128 | 127 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ( ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  ⊤ )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) | 
						
							| 129 | 128 | or32dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ( ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  ∨  ¬  ⊤ ) ) ) | 
						
							| 130 | 126 129 | cnfn2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) | 
						
							| 131 | 124 130 | cnfn1dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) | 
						
							| 132 | 131 | a1dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) | 
						
							| 133 | 132 | a1dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) ) | 
						
							| 134 |  | ax-1 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) ) ) | 
						
							| 135 |  | tsim3 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) )  ∨  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) ) ) | 
						
							| 136 | 135 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) )  ∨  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) ) ) ) | 
						
							| 137 | 134 136 | cnf2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V )  →  ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) ) | 
						
							| 138 | 133 137 | contrd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V ) ) | 
						
							| 139 | 138 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ⊥  →  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V )  ∨  ¬  𝑦  ∈  V ) ) ) | 
						
							| 140 | 115 139 | cnfn1dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ( ¬  ⊥  →  ¬  𝑦  ∈  V ) ) | 
						
							| 141 | 110 140 | contrd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) )  →  ⊥ ) | 
						
							| 142 | 141 | efald2 | ⊢ ( ( ¬  ∃ 𝑦 𝜑  →  𝑦  ∈  V )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) | 
						
							| 143 | 101 142 | ax-mp | ⊢ ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  𝑦  ∈  V ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) | 
						
							| 144 | 13 143 | ax-mp | ⊢ ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) | 
						
							| 145 |  | ax-1 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 146 |  | tsim3 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) )  ∨  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 147 | 146 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) )  ∨  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) ) | 
						
							| 148 | 145 147 | cnf2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ¬  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 149 |  | tsim2 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ∃ 𝑦 𝜑  ∨  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 150 | 149 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  ∃ 𝑦 𝜑  ∨  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 151 | 148 150 | cnf2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ¬  ∃ 𝑦 𝜑 ) ) | 
						
							| 152 |  | tsim2 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  ∨  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 153 | 152 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  ∨  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) ) | 
						
							| 154 | 145 153 | cnf2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) | 
						
							| 155 | 151 154 | mpdd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) | 
						
							| 156 |  | id | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 157 |  | id | ⊢ ( ¬  ( ∃ 𝑦 𝜑  →  𝜓 )  →  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) ) | 
						
							| 158 | 157 | a1i | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ( ∃ 𝑦 𝜑  →  𝜓 )  →  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) | 
						
							| 159 |  | tsim2 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ∃ 𝑦 𝜑  ∨  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) | 
						
							| 160 | 159 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ( ∃ 𝑦 𝜑  →  𝜓 )  →  ( ∃ 𝑦 𝜑  ∨  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 161 | 158 160 | cnf2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ( ∃ 𝑦 𝜑  →  𝜓 )  →  ∃ 𝑦 𝜑 ) ) | 
						
							| 162 | 149 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ( ∃ 𝑦 𝜑  →  𝜓 )  →  ( ¬  ∃ 𝑦 𝜑  ∨  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 163 | 161 162 | cnfn1dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ( ∃ 𝑦 𝜑  →  𝜓 )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 164 | 163 | a1dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ( ∃ 𝑦 𝜑  →  𝜓 )  →  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 165 | 156 164 | mt3d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ∃ 𝑦 𝜑  →  𝜓 ) ) | 
						
							| 166 | 165 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) | 
						
							| 167 |  | tsim3 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) )  ∨  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 168 | 167 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) )  ∨  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) ) | 
						
							| 169 | 148 168 | cnf2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ¬  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 170 |  | tsim3 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 171 | 170 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) ) | 
						
							| 172 | 169 171 | cnf2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 173 |  | tsbi1 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 174 | 173 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) )  ∨  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 175 | 172 174 | cnf2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 176 | 166 175 | cnfn2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ¬  𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V ) ) ) | 
						
							| 177 |  | trud | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ⊤ ) | 
						
							| 178 | 177 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ⊤ ) ) | 
						
							| 179 |  | tsbi3 | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  ⊤ )  ∨  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) | 
						
							| 180 | 179 | a1d | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  ⊤ )  ∨  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) | 
						
							| 181 | 180 | or32dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  ∨  ¬  ⊤ ) ) ) | 
						
							| 182 | 178 181 | cnfn2dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ∨  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) ) | 
						
							| 183 | 176 182 | cnf1dd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ( ¬  ⊥  →  ¬  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) ) ) | 
						
							| 184 | 155 183 | contrd | ⊢ ( ¬  ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) )  →  ⊥ ) | 
						
							| 185 | 184 | efald2 | ⊢ ( ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ⊤ ) )  →  ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) ) | 
						
							| 186 | 144 185 | ax-mp | ⊢ ( ¬  ∃ 𝑦 𝜑  →  ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) ) | 
						
							| 187 | 100 186 | pm2.61i | ⊢ ( 𝑦  =  ( 𝑓 ‘ 𝑥 )  →  ( 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  ↔  ( ∃ 𝑦 𝜑  →  𝜓 ) ) ) | 
						
							| 188 | 19 2 187 | ac6s3f | ⊢ ( ∀ 𝑥  ∈  𝐴 ∃ 𝑦 𝑦  ∈  if ( ∃ 𝑦 𝜑 ,  { 𝑦  ∣  𝜑 } ,  V )  →  ∃ 𝑓 ∀ 𝑥  ∈  𝐴 ( ∃ 𝑦 𝜑  →  𝜓 ) ) | 
						
							| 189 | 17 188 | ax-mp | ⊢ ∃ 𝑓 ∀ 𝑥  ∈  𝐴 ( ∃ 𝑦 𝜑  →  𝜓 ) |