1 | 1. Q: Formula Prop 2. x:{x:Formula| Q(x) }, y:Formula. Dec(x = y) 3. x1: Var y:Formula. Dec( x1 = y) |
2 | 1. Q: Formula Prop 2. x:{x:Formula| Q(x) }, y:Formula. Dec(x = y) 3. x: Formula 4. Q(x) y@0:Formula. Dec(  x = y@0) |
3 | 1. Q: Formula Prop 2. x:{x:Formula| Q(x) }, y:Formula. Dec(x = y) 3. x1: {x:Formula| Q(x) } 4. x2: Formula 5. Q(x2) y@0:Formula. Dec(x1  x2 = y@0) |
4 | 1. Q: Formula Prop 2. x:{x:Formula| Q(x) }, y:Formula. Dec(x = y) 3. x1: {x:Formula| Q(x) } 4. x2: Formula 5. Q(x2) y@0:Formula. Dec(x1  x2 = y@0) |
5 | 1. Q: Formula Prop 2. x:{x:Formula| Q(x) }, y:Formula. Dec(x = y) 3. y2: {x:Formula| Q(x) } 4. y3: Formula 5. Q(y3) y@0:Formula. Dec(y2   y3 = y@0) |