Non-classical Logics

• Non-Monotonicity

  (As more knowledge comes in, we have to revise earlier beliefs).

  • ``Birds fly'' (general rule inferred from examples)
  • ``Penguins are birds''
  • ``Penguins can't fly''

• Resource Constraints
  • If I have 5 Rupees, I can buy coffee
  • If I have 5 Rupees, I can buy tea
  • If I have 5 Rupees, I can buy coffee and I can buy tea