Courses/Computer Science/CPSC 203/CPSC 203 2007Fall L04/CPSC 203 2007Fall L04 Lectures/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 : http://en.wikipedia.org/wiki/Allometric_law
- Fractal Branching. E.g. for the May Equation (also called the "Logistic Map"): Xt+1 = rxt(1-xt)
- For more on the May Equation/ Logistic Map see: http://en.wikipedia.org/wiki/Logistic_map
- For more on scaling as it applies to equations similar to the Logistic Map see: http://en.wikipedia.org/wiki/Feigenbaum_function (warning -- this reference is more "math technical" -- just note the function is in the form of a (complicated) power law.
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
- Self-Policed and Editted (Wiki Gnomes and Gremlins).
- The original 'definition' of a Wiki Gnome is at: http://c2.com/cgi/wiki?WikiGnome
- 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: http://c2.com/cgi/wiki -- 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: http://en.wikipedia.org/wiki/Design_pattern_(computer_science). Ward Cunningham, creator of the Wiki concept also made a number of contributions in this area.