1. Subproject 3 Large Scale Optimization Participants CTI, CUNI, MPII, RWTH, TU Wroclaw, UCY, UPB presented by Burkhard Monien (UPB)

2. Burkhard Monien (UPB) Large Scale OptimizationSubproject 3 Goals of SP3 „Large Scale Optimization“ Long term new approximation theory, methodological framework and software implementations for large-scale optimization problems. Short term Identification of key problems, initial modellings, approximation algorithms for large-scale optimization problems. Approximation theory Algorithms Implementations Documentation Large-scale wired networks, network problems, wireless networks Introduction

3. Burkhard Monien (UPB) Large Scale OptimizationSubproject 3 Structure of SP3 „Large Scale Optimization“ WP 3.1 Approximation Techniques for Large-Scale Optimization WP 3.2 Optimization Methods for Large-Scale Communication and Transportation Networks and the Web WP 3.3 Foundations Of Wireless Networks WP 3.4 A Compendium of Large-Scale Optimization Problems Introduction

4. Burkhard Monien (UPB) Large Scale OptimizationSubproject 3 Publications Total ??? conference / journal papers, ??? reports under submission Last 12 Month ??? conference / journal papers, ??? reports under submission Introduction

5. Burkhard Monien (UPB) Large Scale OptimizationSubproject 3 Deliverables due at month 24 D3.1.3: Establishment of Basic Methodological Framework of Nonlinear Optimization Approaches for Large-Scale Optimization Problems D3.2.2: Initial Modeling of Selected Problems for Communication/Transportation Networks D3.3.3: Assessment of Developed Algorithmic Techniques D3.4.3: Initial Experimental Studies of Selected Problems Introduction

6. Burkhard Monien (UPB) Large Scale OptimizationSubproject 3 External Memory (Meyer & Ajwani, MPII) main memory size << problem size external memory = D disks data is transferred in blocks of size B up to D · B data per I/O operation Goal: minimize number of I/O operations scan(x) = O ( x / (D · B) ) sort(x) = O ( x / (D · B) · log M/B (x/B) )

7. Burkhard Monien (UPB) Large Scale OptimizationSubproject 3 Breadth First Search (BFS)

8. Burkhard Monien (UPB) Large Scale OptimizationSubproject 3 Breadth First Search (BFS)

9. Burkhard Monien (UPB) Large Scale OptimizationSubproject 3 External BFS — Motivation Solving real world optimization problem often boils down to structured graph traversal Crawling, analyzing the WWW Generalizations: Shortest Paths, A* Route planning using small navigation devices with flash memory cards State space exploration

10. Burkhard Monien (UPB) Large Scale OptimizationSubproject 3 External BFS — Experimental Study A computational study of three BFS-algorithms from the literature D. Ajwani, R. Dementiev, U. Meyer, SODA'05 (DELIS-TR-0276) Internal-memory algorithm Munagala, Ranade SODA'99 Mehlhorn, Meyer ESA'02

11. Burkhard Monien (UPB) Large Scale OptimizationSubproject 3 The End Thank you!