We consider the problem of securing a graph against a sequence of vertex attacks by placing guards on its vertices. The guards are “mobile” in that, after any attack, each guard can move to any neighbor of its current location, but one guard must move to the attacked vertex. We determine sharp upper bounds, in terms of the order of the graph, on the minimum number of guards necessary for connec...

The art gallery problem [2] asks for the smallest possible size of a point set S (the guards) to completely guard the interior of a simple polygon P (the art gallery). This thesis treats variations of the original problem that arise when we introduce a coloring of the guards. Rather than asking for the minimum number of guards we ask for the minimum number of colors. In [4] L. H. Erickson and S...

As rising crime rates have evoked expressions of fear nationwide, citizens have become increasingly concerned with residential security measures. In response to this growing fear, one form of action undertaken by residents has been the formation of residential patrols and guards. This study examines, from an economic standpoint, who the participants are in such endeavors, and how participation ...

We consider the wireless localization problem. Given a simple polygon P , place and orient guards each of which broadcasts a unique key within a fixed angular range. At any point in the plane one must be able to tell whether or not one is located inside P only by looking at the set of keys received. In other words, the interior of the polygon must be described by a monotone Boolean formula comp...

This paper describes a model for developing applications of active object-oriented databases based on three orthogonal concepts; methods, guards and actions and a tool which implements these ideas called MGA. MGA objects are active; they have guards which constrain the object's state, actions which maintain database integrity when the object's state changes and methods through which the object ...