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Web Science: AnalyZing the Web

Web Science: AnalyZing the Web. Graph Terminology. Graph ~ a structure of nodes/vertices connected by edges The edges may be directed or undirected Distance ~ shortest # of edges connecting 2 vertices Diameter ~ greatest distance b/w any 2 vertices of a graph.

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Web Science: AnalyZing the Web

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  1. Web Science: AnalyZing the Web

  2. Graph Terminology • Graph ~ a structure of nodes/vertices connected by edges • The edges may be directed or undirected • Distance ~ shortest # of edges connecting 2 vertices • Diameter ~ greatest distance b/w any 2 vertices of a graph http://en.wikipedia.org/wiki/Graph_(data_structure)

  3. Web graph • Web graph ~ Directed graph that is formed by webpages and their hyperlinks • Sub-graph is a set of pages linked to one specific topic http://googlesystem.blogspot.com/2007/05/world-wide-web-as-seen-by-google.html

  4. Web graph features • Bow-tie structure of the web graph • IN-links go to a Strongly Connected Core (SCC) of web pages • SCC pages link to all other SCC pages (e.g. paulbui.net/wl) • OUT-links leave the SCC, and you cannot get back

  5. Web Graph Application to PageRank • Google PageRank algorithm used web graphs http://en.wikipedia.org/wiki/PageRank

  6. Traveling Salesman Problem (not-IB) • Given a list of cities and the distances between each pair of cities, what is the shortest possible route that visits each city exactly once and returns to the origin city? • http://en.wikipedia.org/wiki/Travelling_salesman_problem

  7. Traveling Salesman Problem cont’d http://imgs.xkcd.com/comics/travelling_salesman_problem.png

  8. Power laws and web development • Moore’s Law • # of transistors on integrated circuit doubles about every two years • Exponential growth of power • Exponential decay of cost • Examples: • CPUs • Flash drives • Metcalfe’s Law • Usefulness of a network ~ n^2 n(n − 1)/2  n^2 http://en.wikipedia.org/wiki/Metcalfe's_law

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