ABSTRACT
Contents 15.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392 15.2 Topological Robustness of Biological Systems . . . . . . . . . . . . . . . . . . . . . . . . . . 393
15.2.1 Overview of Biological Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393 15.2.2 Resemblance between Biological Systems and Information
Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394 15.2.3 Topological Characteristic of Biological Networks . . . . . . . . . . . . . 394
15.2.3.1 Scale-Free Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394 15.2.3.2 Bow-Tie Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395 15.2.3.3 Hierarchical Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395 15.2.3.4 Modularity Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396
15.3 Modularity and Robustness of Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396 15.3.1 Attack Vulnerability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397 15.3.2 Isolation and Localization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398
15.3.3 Bottleneck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 15.3.4 Adaptability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402
15.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405
Biological systems have evolved to withstand perturbations, and this property, called robustness, is the most commonly and ubiquitously observed fundamental systemlevel feature in all living organisms. Thus, understanding biological systems naturally drives us to discover the origin of robustness, and this discovery will help us to design more robust man-made systems. In this chapter, we explore topological robustness based on the insights gained from the understanding of biological systems.
