In logic programming, the well-founded semantics is one definition of how we can make conclusions from a set of logical rules. In logic programming, we give a computer a set of facts, and a set of "inference rules" about how these facts relate. There are several different ways that we might want the computer to apply these rules; the well-founded semantics is one of these ways.
Read more about Well-founded Semantics: History, Relations To Other Models, Applications, Complexity and Algorithms