Title: Imprecision in Computational Geometry Abstract: Given a set of points in the plane, various measures exist that try to capture certain properties of that point set. Examples of such measures include the \emph {diameter}: the largest distance between any pair of points, the \emph {closest pair}: the smallest distance between any pair of points, the \emph {width}: the smallest distance between two parallel lines with all points between them, the smallest circle containing all points, or the smallest axis-aligned bounding box containing all points. All these measures have been well studied and optimal algorithms to compute them are known. When dealing with real-world data, however, locations of input points are often not known exactly. If we know for each point that it lies inside some region, but not where in that region, it becomes interesting to compute bounds on the possible values of these basic geometric measures. To make this more precise, we are given a set of regions in the plane $\script L \subset \script P (\Rn2)$ and a measure $\mu : \script F (\Rn2) \to \R$ that takes a set of points and gives a real number, and we want to place one point in each region of $\script L$ such that the resulting point set maximises or minimises $\mu$.