Special issue on temporal representation and reasoning (TIME’13)

In September 2013, we organized the 20th International Symposium on Temporal Representation and Reasoning (TIME’13) that took place in Pensacola, FL (USA). After 20years, the Symposium returned to the venue where it originally started. TIME has grown since its original incarnation as a workshop to become an international symposium encompassing several different areas of computer science which deal, in some way or another, with the concept of time, its representation, reasoning and applications. This event has provided an opportunity for scientific exchange for researchers coming from different areas such as artificial intelligence, databases, temporal logic, and formal methods. The work presented at the 2013 Symposium concerned several different temporal aspects of information and computation and comprises a unique combination of innovative theoretical results and successful applications. This special issue of Acta Informatica originates from a call for papers sent out right after the symposium, in which we invited the authors of the highest ranked papers—according to the reviews carried out by the Program Committee members—to submit an extended version. After two rounds of reviews performed by additional experts the following papers were selected for publication in the special issue.We thank all reviewers for their commitment and dedication. The paper “A Faster Execution Algorithm for Dynamically Controllable Simple Temporal Networks with Uncertainty”, by Luke Hunsberger, presents novel algorithms for managing the execution of dynamically controllable simple temporal networks with uncertainty. For the first time, full proofs of the correctness of these algorithms in a self-contained manner are presented. The paper “Optimization in Temporal Qualitative Constraint Networks” by Jean-Francois Condotta, Souhila Kaci and Yakoub Salhi presents a variety of results about temporal quali-