Deimos: Proof Help

Defeasible Logic

There are two levels of proof available.

(1) The definite level.

This level only uses facts and rules with -> in them. To prove x at this level, type

+D x

(2) The defeasible level.

This level uses all the facts, rules and the priority (>) information. To prove x at this level type

+d x

This system can also prove that formulas cannot be proved.

To prove that +D x cannot be proved, type

-D x

To prove that +d x cannot be proved, type

-d x

The positive (+) and negative (-) kinds of proof are related as follows.

Let P be D or d.

If +P x then not -P x.

If -P x then not +P x.

The levels of proof are related as follows.

If +D x then +d x.

If -d x then -D x.

Defeasible Logic Variants

The dt level of proof does not feature team defeat, but is otherwise the same as the d defeasible level of proof.

The da level of proof features ambiguity propogation, making it a slightly stronger level of proof than the d defeasible level of proof. It is defined in terms of a weaker level, S, support.