Link Analysis and Visualization

Analysis and Visualization of Large Networks Using Pajek Vladimir Batagelj (University of Ljubljana) The first part of the contribution is a short overview of program Pajek. Pajek (Slovene word for Spider) is a program, for Windows (32 bit), for analysis and visualization of large networks. It is freely available, for noncommercial use, at its homepage: http://vlado.fmf.uni-lj.si/pub/networks/pajek/ I am developing Pajek together with Andrej Mrvar. Some procedures were contributed also by Matjaž Zaveršnik. The main goals in the design of Pajek are: • to support abstraction by (recursive) factorization of a large network into several smaller networks that can be treated further using more sophisticated methods; • to provide the user with some powerful visualization tools; • to implement a selection of efficient (subquadratic) algorithms for analysis of large networks. Besides ordinary networks, that can be imported in several formats (Pajek’s native, Ucinet DL, GEDCOM, ball and stick, MDL, Vega), Pajek supports also 2-mode networks and temporal networks. Pajek is based on six data structures: network, partition, cluster, permutation, hierarchy and vector. It is essentially a collection of routines operating on these data structures. Typical sequences of applications of routines can be ’encapsulated’ as macros. We developed efficient algorithms for determiningmain paths in acyclic networks, cores and counting triads.