Privacy-Preserving Biometric Authentication: Challenges and Directions

Figure 2

An intuitive example of what the set-covering problem is. The aim is to cover the largest possible area in the space using 5 circles. On (a), the centres of the circles are chosen at random (the covered area is less than ), while on (b), we provide a better covering of the space (the covered area is about ). Finding the optimal covering corresponds to solving an NP-hard problem for large dimensions of the space.

(a)

(b)