In this paper, we explore complex network properties of word collocation networks (Ferret, 2002) from four different genres. Each document of a particular genre was converted into a network of words with word collocations as edges. We analyzed graphically and statistically how the global properties of these networks varied across different genres, and among different network types within the same genre. Our results indicate that the distributions of network properties are visually similar but statistically apart across different genres, and interesting variations emerge when we consider different network types within a single genre. We further investigate how the global properties change as we add more and more collocation edges to the graph of one particular genre, and observe that except for the number of vertices and the size of the largest connected component, network properties change in phases, via jumps and drops.
A document is represented by a network; the nodes represent terms, and the edges represent the co-occurrence of terms. This paper shows that the network has the characteristics of being small world, i.e., highly clustered and short path length. Based on the topology, we can extract important terms, even if they are rare, by measuring their contribution to the graph being small world.  Co-occurrence networks of Chinese characters are constructed from collections of essays in different periods of China: the ancient Chinese language, the Chinese language in Wei, Jin, and Southern-Northern Dynasties, the recent Chinese language, and the modern Chinese language, and their statistical parameters are studied. It has been found that 99.6 networks have the scale-free feature and 95.0 networks have the smallworld effect. This study reveals some commonalities and differences among articles in different periods of China from a complex network perspective. There has been a controversial question as to whether the literatures in Wei, Jin, and Southern-Northern Dynasties should belong to the ancient Chinese language or the recent Chinese language in the linguistic study. Our work shows that the statistical parameters of networks in Wei, Jin, and Southern-Northern Dynasties are clearly different from those of networks in the other periods of China, and it seems more reasonable that the literatures in Wei, Jin, and Southern-Northern Dynasties belong to the recent Chinese language.