1. Median trajectories: define and compute a trajectory composed of the input trajectories and that is somehow in the middle Marc van Kreveld Department of Information and Computing Sciences Utrecht University Geometric algorithms for GIScience (analysis, visualization) with Kevin Buchin, Maike Buchin, Maarten Loffler, Rodrigo Silveira, Carola Wenk, and Lionov Wiratma (ESA 2010)

2. Most similar subtrajectory: find a subtrajectory in both trajectories of the same duration and that are as similar as possible with Kevin Buchin, Maike Buchin, and Jun Luo (SIGSPATIAL 2009) with Maike Buchin, Anne Driemel, and Vera Sacristan (SIGSPATIAL 2010) Trajectory segmentation: split a trajectory into pieces that are “similar” within each piece, but not from one piece to the next

3. Longest flock: determine the subgroup that stays together longest Approximation algorithms for motion patterns (flocking, convergence, encounter) with Joachim Gudmundsson (ACM GIS 2006) with Joachim Gudmundsson and Bettina Speckmann (ACM GIS 2004) Motion patterns (flocking, convergence, encounter) with Patrick Laube and Stephan Imfeld (Spatial Data Handling 2004) My problem: Can we define and compute spatio-temporal association rules involving trajectories?