Networks

Add by mariopaolucci | May 08, 2012 11:33  1548 |  10
Networks
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Networks
1 Diagram of Internet connections, showing the major Metropolitan Area Exchanges (MAE), by K.C. Claffy,
2 What IS a network?
2.1 Comparison with the grid
2.1.1 fixed number of neighbors
2.1.1.1 exception: continuous space
2.2 Networks in sociology
2.2.1 The study of networks in sociology began very early. A network is the perfect instrument for keeping track of the relations between people and to study group dynamics, for example, finding out who is friend with who in a classroom; networks are studied for transmission of diseases, and so on. Study on social networks started in to the 1920s, with Moreno's book on sociograms and socio matrices [moreno1934shall] normally cited as the intial milestone. Moreno's socio matrix simply represented the relations as matrix elements - the relation between the element i and the element j would be present (and have a sign, or a value representing an intensity) if the value m_{j}^{i} is different from zero; the value can represent, as in the example above, a friendship value, a contagion flag, the number of intercourses, that have been calculated between the indivuals in question. Today, as we have developed better represenations, these matrix appear cumbersome and unnecessary.
2.3 Examples of networks
2.3.1 Examples of networks being currently studied are countless: they include co-authorship networks in science (often differentiated per discipline), collaborations between actors, sitting in the same boards for company directors, the Internet, food webs, that is, who-eats-who between animals, interactions between proteins, and so on.
2.3.1.1 Fonts and examples
2.3.1.1.1 Linked
2.3.1.1.1.1 Cover
2.3.1.1.1.1.1 http://www.bearcave.com/bookrev/linked/
2.3.1.1.1.1.2 http://andreas.com/faq-barabasi.html
2.3.1.1.1.2 What next?
2.3.1.1.1.2.1 Bursts!
2.3.1.1.1.2.1.1 http://www.barabasilab.com/
2.3.1.1.2 Graph structure in the web
3 Networks as graphs
3.1 Networks, in fact, are simple mathematical concepts and can be expressed elegantly with a set of (ordered) couples. If we have a set of nodes
3.1.1 N1.. NN
3.1.2 then we can generate couples from this set:
3.1.3 (N1, N3) (N2, N5)....
3.2 9.1.1 Simple measures on a network
3.2.1 grade
3.2.2 maximum number of links
3.2.3 density
3.2.4 Clustering Coefficient
3.2.5 Components
3.2.6 Diameter
3.2.7 Assortativity
3.3 Network measures in NetLogo
3.3.1 Netlogo basic instructions for networks
3.3.1.1 Creation
3.3.1.1.1 create-link-with
3.3.1.1.2 create-link-from, create-link-to
3.3.1.2 Exploration
3.3.1.2.1 link-neighbors
3.3.1.2.2 in-link-neighbors, out-link-neighbors
3.3.1.2.3 end1, end2, other-end (from links)
4 9.2 The giant component
5 Three insights on networks
5.1 9.3.1 Clue n.1: It's a small world
5.2 9.3.2 Clue n. 2: The strength of the weak links.
5.3 9.3.3 Clue n. 3: Power laws
5.3.1 Subtopic 1
5.4 Subtopic 4
6 9.4 Preferential attachment
6.1 9.4.1 NetLogo implementation
6.1.1 Topic
7 9.5 Networks and security
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