Saying You Are There

In reasoning about events and change, we confront a variety of problems which make the inference of even seemingly obvious conclusions very difficult. A key problem is the need to assume that you have sufficient information to make reliable inferences, Amsterdam's "You Are There Convention". This has led to a proliferation of non-monotonic logics where the sufficient information assumption is embedded in the semantics. However, these approaches have some serious shortcomings. Avoiding these problems, Schubert's Explanation Closure approach states the sufficient information assumption axiomatically, allowing standard monotonic semantics. These axioms state the assumption indirectly and are stronger than needed, so they result in otherwise unwarranted inferences and restrictions on interpretations. In this paper we describe a monotonic formalism with a rich language of events in which the sufficient information assumption can be stated directly. As a result, it avoids the ontological re..