A Logical Semantics for Nonmonotonic Sorts

Suppose we have a feature system, and we wish to add default values in a well-deened way. We might start with Kasper-Rounds logic, and use Reiter's example to form it into a default logic. Giving a node a default value would be equivalent to saying \if it is consistent for this node to have that value, then it does." Then we could use default theories to describe feature structures. The particular feature structure described would be the structure that supports the extension of the default theory. This is, in eeect, what the theory of nonmonotonic sorts gives you. This paper describes how that theory derives from what is described above.