Depto. Investigación Operativa, Computer Science Institute, Engineer Faculty Universidad de la República, Uruguay

1. Depto. Investigación Operativa,Computer Science Institute,Engineer Faculty Universidad de la República, Uruguay March 2005

2. Assistants Celina Gutiérrez Antonio Mauttone Alfredo Olivera Martín González Pablo Rodríguez Bocca Eight PhD and MsC students Students working on their degree dissertations. Staff of the group • Professors • Héctor Cancela • María E. Urquhart • Omar Viera • Carlos Testuri • Franco Robledo • Graciela Ferreira • Daniel Meerhoff

3. Courses • Introduction to Operation Research. • Extensions to Linear Programming and Integer Programming. • Metaheuristics solving Combinatorials Problems. • Optimization under uncertainty. • Discrete Event Simulation. • E-commerce and OR.

4. Methodologies Optimization Heuristics, meta-heuristics. Mathematical programming, in particular stochastic programming and dynamic programming. Simulation Discrete event simulation. Monte Carlo methods, Variance Reduction methods. Main research areas and methodologies • Main application areas • Transportation, • Logistics, • Communications. • Cooperation areas • High performance Computing. • Other areas of interest • Finance, • Electricity networks, • Re-engineering.

5. Transportation • Vehicle routing • “Cluster first, route second" methods (Omar Viera, Libertad Tansini, Daniel Giosa, Marita Urquhart) • Routing heuristics. • Assignment heuristics, Genetic Algorithms. • Metaheuristics • Ant Systems (Hector Cancela, Omar Viera). • Adaptive memories (Alfredo Olivera, Omar Viera).

6. Article “Adaptative Memory Programming for the Vehicle Routing Problem With Multiple Trips”. A. Olivera, O. Viera (2005) • Difficulty: each vehicle may perform several routes in the same planning period, it implies the design of a set of routes and the assignmentnt of those routes to the available vehicles. • Heuristic based on AMP (Rochat and Taillard). • Tested over the 104 benchmark problems proposed by Taillard et.al.

7. Transportation • Urban public transport(H.Cancela, M.E. Urquhart, A. Mauttone. O. Viera) • Bus line simulation. • Origin-destination-time demand matrix estimation. • Bus line design. • Intelligent Transport Systems. • Vertical transport(H. Cancela, O. Viera) • Capacity estimation. • Simulation and comparison of scheduling algorithms.

8. Extended Abstract and Posters • “Bus lines design in urban public transport” A.Mauttone, M.E. Urquhart (ICIL Poster-2005). • “GRASP multiobjetivo para el diseño de rutas y frecuencias en transporte colectivo público” (CLAIO 2004) This work is about the design of bus lines (routes and frequencies) in urban public transport systems. It is part of a long reach project, whose objective is to develop a tool that supports the transit network design planning in a strategic context. Characteristics • High combinatorial complexity. • Multi-objective nature: objectives of users and operators expressed in different units, and usually contradictory (an improvement in one objective implies a detriment in the other one). • Mixed variables: discrete variables represent the sequences of nodes in each bus route, and continuous variables represent the bus frequencies. • Real Case study with real data

9. Communication networks • Wide Area Network topology design(H. Cancela). • Steiner trees, 2-connected networks, Generalized Steiner problems in graphs: • Ant Systems • GRASP (F. Robledo) • Genetic Algorithms • Other heuristics. • Topology design with uncertain demands(stochastic programming)(C. Testuri).

10. Networks • Reliability models (H.Cancela) • Classical models: evaluation using variance reduction techniques. ( and G. Rubino) • Models with distance restrictions. (and L. Petingi) • Optimization - GRASP, Genetic Algorithms. • Peer-to-peer network models. • Performance evaluation of computer clusters • Petri networks. • Markov chains, simulation.

11. Article • “Network design with node connectivity constraints” H. Cancela, F. Robledo, G. Rubino.(2004) Problem: to find the least costnetwork topology that satisfies some node-disjoint path connection requirements; Modeled as a GSPNC (Generalized Steiner Problem with Node-Connectivity Constraints); Solved with an algorithm based on GRASP. Present experimental results, test problems with more than 100 nodes, obtained from public libraries.

12. Article • “A GRASP algorithm with RNN based local search for designing a WAN acces network” H. Cancela, F. Robledo, G. Rubino.(2004) Problem: to design the access network topology of a Wide Area Network; Modeled as a variant of the Steiner Problem in graphs. Solved with an algorithm based on GRASP that employs Random Neural Networks as local search heuristic. Present experimental results, test problems obtained from the SteinLib .

13. Article • “Evolutionary algorithms applied to reliable communication network design” S. Nesmachnow,H. Cancela, E. Alba.(2004) Problem: to design a reliable communication network topology; Modeled as a Generalized Steiner Problem in graphs (to design a minimum cost subnetwork verifying a set of prefixed minimum connection requirements for pairs of terminal nodes). Solved with a set of pure and hybrids Evolutionary algorithms (GA, CHC, GA+SA, Parallel) Present a comparative study of them with a random test suite of three .

14. Technical reports • “Diseño de redes de Comunicaciones con Incertidumbre en la demanda” Degree dissertation. J. Viera,C. Testuri.(2004) Multicommodity network, Sotchastic Programming. • “Motor de metaheurísticas para el problema de asignación de salones de la Facultad de Ingeniería” S. Costabel, M. Urquhart (2005). Master thesis. Timetable problem, Tabu-Search, Genetic Algorithm, Ant-systems. Real test-case: Engineering Faculty.

15. Simulation, other topics • Discrete event simulation(H.Cancela. M.Urquhart). • Scheduler for DES. L.Murray • Bus line design. A. Mauttone et.al

16. Projects with industry and public sector • CoNaProLe: truck routing for milk collection. • IMM, IMR: urban public transport studies. • ANCAP / DUCSA: preliminary study of opportunity areas for optimization. • MGAP: study of organization of computing center. • BPS: third party services..

17. International cooperation • INRIA (Institut National de Recherche en Informatique) Rennes, Francia: Team “Planning of Architecture and Infrastructre of Networks” , joint projects, students co-direction. (Communication Networks design) • City University of New York: joint projects.(Networks design –diameter restriction) • PROSUL network “Discrete optimzation and graphs: theory, algorithms and applications”: USP, UFRJ, U. Chile, UBA, U. Rosario, etc. • ALFA network “Solving real problems of high complexity in combinatorial optimization”: U. Bologna, Avignon, L. de Bruselas, U. Concepción, etc. Students co-direction.

18. Events organized • IV and X ELAVIO (Escuela Latinoamericana de Verano de Investigación Operativa): Montevideo 1997, 2004. • ICIL 2005 (International Conference on Industrial Logistics): Montevideo, february 2005. • CLAIO 2006 (Congreso Latino Ibero Americano de Investigación de Operaciones): Montevideo, november 2006.