title | date | lastmod |
---|---|---|
Default Logic |
2022-11-08 |
2022-11-21 |
A closed default is one that has been instantiated The In-set contains all the consequences from applying a default The Out-set contains all the negations of the justifications from applying a default: these are the predicates which cannot be proven true by the In-Set for the extension to be consistent
- Start with the root node: Out is initialized to
$\emptyset$ while In is set to the current knowledge base - For every node, check for direct applicability of defaults (If no defaults are directly applicable: we arrived at a closed process) direct applicability must satisfy 2 conditions:
- Default must be triggered: In-set contains the prerequisite
- Default must be justified: negation of justifications cannot be proven True from the current In-set
- If the new In-set becomes inconsistent (
$In \cap Out \neq \emptyset$ or$In\cup \delta .consq \ \vdash Out$ ) : process is unsuccessful
We arrive at an extension for every closed and successful process.