Supplement to Defeasible Reasoning
A Popper function is a function from pairs of propositions to real numbers that satisfies the following conditions:
- For some D, E, P[D|E] ≠ 1.
- P[A|A] = 1.
- P[A|(C & B)] = P[A|(B & C)].
- P[(B & A)|C] = P[(A & B)|C].
- P[A|B] + P[¬A|B] = 1, or P[C|B] = 1.
- P[(A & B)|C] = P[A|(B & C)] × P[B|C].