The authors discuss the problem of detecting commuting patterns in a trajectory (i.e., to detect a common movement pattern of a group of entities). By the Fréchet distance between subtrajectories (since they are invariant under differences in speed), the measurement for spatial similarity is performed to find similar subtrajectories within a given trajectory. The authors also give approximation algorithms for this problem and prove that the longest subtrajectory cluster problem is as hard as $\mathsf{MAXCLIQUE}$ to approximate.
Reviewer: Jong Hyuk Park (Ulsan)