The second topic are parallel algorithms, based on an algebraic abstraction of the Moore-Bellman-Ford algorithm, for solving various distance problems. Our focus are distance approximations that obey the triangle inequality while at the same time achieving polylogarithmic depth and low work.
Finally, we study the continuous Terrain Guarding Problem. We show that it has a rational discretization with a quadratic number of guard
candidates, establish its membership in NP and the existence of a PTAS, and present an efficient implementation of a solver.