Courses/Computer Science/CPSC 203/CPSC 203 2007Fall L04/CPSC 203 2007Fall L04 Lectures/Lecture 3

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Lecture 3

We continue with the "Only Connect" lecture on the large-scale structure of the Internet

The objectives of today's class are:

  • House Keeping
    • Review Course Lecture Schedule
    • Introduce Term Projects
  • "Only Connect" continued (Describe the Origins of the Internet, it's structure, and how that structure is evolving. Link Internet structure to its capabilities and limitations)
    • Glossary Review & Alternate Cartoon History of Internet
    • Scale Free and Power Laws
    • Wiki's -- An example of connecting and collaborating

Scale Free Networks and Power Laws

  • Scale Free Networks are Examples of Power Laws
  • Power laws are of the form: P(K) ~ 1/K ** B -- Yikes, MATH! What does this mean?
  • It means: P(K) is the Probability that a node in the network, connects with K other nodes. The coefficient "B" varies between 2-3 for most real networks.
  • Other Examples of scaling:
    • Plant Productivity/ Area
    • Bone length and cross-sectional area
    • The above are examples of "Allometric Relationships" where two attributes of an organism maintain a power-law relationship. See :
    • Fractal Branching. E.g. for the May Equation (also called the "Logistic Map"): Xt+1 = rxt(1-xt)

Wiki Wiki World

  • Invented by Ward Cunningham as "the simplest online database that could possibley work".
  • Wikiwiki is a Hawaiian verb meaning -- fast, speedy; to hurry, quick fast, swift.
  • Originally used for programmers -- Portland Pattern Repository
  • Essentially Form Based (Web 1.0) technology

Key Wiki Technical Features

  • Edittable Web Page
  • Small Markup Language for formatting and linking
  • Rollback "database" to previous state

Key Wiki Cultural Features

  • Open
  • Voluntary
  • Self-Policed and Editted (Wiki Gnomes and Gremlins).
  • Collaborative Writing and Editting -- goes to "collective we" voice.
  • Used for: Education, Business Tech Support, "Encylcopedic" overviews -- e.g. Wikipedia., or for learning purposes, such as this class


Original WikiWikiWeb at: -- this housed the original "Portland Pattern Repository" -- a discussion area for programmers to discuss "Design Patterns". If you're curious as to what Design Patterns may be -- see: Ward Cunningham, creator of the Wiki concept also made a number of contributions in this area.