ROBERTO WOLFLER CALVO, LIPN, Université Paris 13We consider shortest paths on time-dependent multi-modal transportation networks where restrictions or preferences on the use of certain modes of transportation may arise. We model restrictions and preferences by means of regular languages. Methods for solving the corresponding problem (called the regular language constrained shortest path problem) already exist. We propose a new algorithm, called State Dependent ALT (SDALT), which runs considerably faster in many scenarios. Speed-up magnitude depends on the type of constraints. We present different versions of SDALT including uni-directional and bi-directional search. We also provide extensive experimental results on realistic multi-modal transportation networks. [Kirchler et al. 2011;Kirchler et al. 2012] Authors' addresses: D. Kirchler, Mediamobile, 27, bld Hippolyte Marqus, 94200 Ivry sur Seine, France. Email: kirchler@lix.polytechnique.fr. L. Liberti, LIX,École Polytechnique, 91128 Palaiseau, France. Email: liberti@lix.polytechnique.fr. R. Wolfler Calvo, LIPN, Univ. Paris 13, Avenue J.B. Clément, 93430 Villetaneuse, France. Email: roberto.wolfler@lipn.univ-paris13.fr. Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies show this notice on the first page or initial screen of a display along with the full citation. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, to republish, to post on servers, to redistribute to lists, or to use any component of this work in other works requires prior specific permission and/or a fee. Permissions may be requested from Publications Dept., ACM, Inc., 2 Penn Plaza, Suite 701, New York, NY 10121-0701 USA, fax +1 (212) 869-0481, or permissions@acm.org. c YYYY ACM 1084-6654/YYYY/01-ARTA $15.00 DOI 10.1145/0000000.0000000 http://doi.acm.org/10.1145/0000000.0000000 ACM Journal of Experimental Algorithmics, Vol. V, No. N, Article A, Publication date: January YYYY.A:2 Dominik Kirchler et al.
INTRODUCTION 11Multi-modal transportation networks include roads, public transportation, bicycle 12 lanes, etc. Shortest paths in such networks must satisfy some additional constraints: 13 passengers may want to exclude some transportation modes, e.g., the bicycle when it is 14 raining or the car at moments of heavy traffic. Furthermore, they may wish to pass by 15 a particular location (e.g., a grocery shop), or limit the number of changes when using 16 different modes of transportation. Feasibility also has to be assured: private cars or 17 bicycles can only be used when they are available.
18The regular language constrained shortest path problem (RegLCSP) deals with this 19 kind of problem. It uses an appropriately labeled graph and a regular language to 20 model constraints. A valid shortest path minimizes some cost function (distance, ti...