%0 Conference Paper %D 2005 %T A motion closed world asumption %A Yaman,F. %A Nau, Dana S. %A V.S. Subrahmanian %X Yaman et. al. [Yaman et al., 2004] introduce “gotheories” to reason about moving objects. In this paper, we show that this logic often does not allow us to infer that an object is not present at a given place or region, even though common sense would dictate that this is a reasonable inference to make. We define a class of models of go-theories called coherent models. We use this concept to define a motion closed world assumption (MCWA) and de- velop a notion of MCWA-entailment. We show that checking if a go-theory has a coherent model is NP-complete. An in atom checks if a given ob- ject is present in a given region sometime in a given time interval. We provide sound and complete al- gorithms to check if a ground in literal (positive or negative in atom) can be inferred from a go- theory using the MCWA. In our experiments our algorithms answer such queries in less than 1 sec- ond when there are up to 1,000 go-atoms per object. %V 19 %P 621 - 621 %8 2005/// %G eng %U http://ijcai.org/papers/1227.pdf