Dictionary of Computer and Internet Terms: default logic (defeasible logic)
default logic (defeasible logic)
a formal system of reasoning in which some facts or rules have priority over others. For example, statements about ostriches might have priority over statements about birds because an ostrich is a specific kind of bird. It is then possible to say without contradiction that birds fly, but ostriches don't fly. In classical logic, "birds fly" and "ostriches are birds" together with "ostriches don't fly" is a contradiction.
Default logic is often used in expert systems.Contrast confidence factor; fuzzy logic.
