A variety of different social, natural and technological systems can be described by the same mathematical framework. This holds from the Internet to food webs and to boards of company directors. In all these situations a graph of the elements of the system and their interconnections displays a universal feature. There are only few elements with many connections, and many elements with few connections. This book presents the experimental evidence of these "Scale-free networks" and provides students and researchers with a corpus of theoretical results and algorithms to analyse and understand these features. The content of this book and the exposition makes it a clear textbook for beginners, and a reference book for the experts.

《计算机网络（第4版）》全书按照网络协议模型（物理层、数据链路层、介质访问控制子层、网络层、传输层和应用层），自下而上系统地介绍了计算机网络的基本原理，并给出了大量实例。在讲述各网络层的同时，还融合进了近年来迅速发展起来的各种网络技术，如Internet、SONET、A DSL、CDMA、WLAN和蓝牙等。另外，针对当前计算机网络的发展现状以及计算机安全的重要性，本书用了一整章的篇幅对计算机安全进行了深入讨论。