# Mobile vs. point guards

## TL;DR

This paper compares the efficiency of horizontal and vertical mobile guards versus point guards in guarding orthogonal art galleries, providing bounds and efficient computation methods for guard placement.

## Contribution

It establishes a sharp bound relating point guards to mobile guards and shows these mobile guard numbers can be computed in linear time.

## Key findings

- Sharp bound on point guards in terms of mobile guards
- Linear-time algorithms for mobile guard coverage
- Comparison of mobile and point guard strategies

## Abstract

We study the problem of guarding orthogonal art galleries with horizontal mobile guards (alternatively, vertical) and point guards, using "rectangular vision". We prove a sharp bound on the minimum number of point guards required to cover the gallery in terms of the minimum number of vertical mobile guards and the minimum number of horizontal mobile guards required to cover the gallery. Furthermore, we show that the latter two numbers can be calculated in linear time.