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- Diagram of Internet connections, showing the major Metropolitan Area Exchanges (MAE), by K.C. Claffy,
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What IS a network?
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Comparison with the grid
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fixed number of neighbors
- exception: continuous space
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Networks in sociology
- 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.
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Examples of networks
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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.
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Fonts and examples
- Linked
- Cover
- http://www.bearcave.com/bookrev/linked/
- http://andreas.com/faq-barabasi.html
- What next?
- Bursts!
- http://www.barabasilab.com/
- Graph structure in the web
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Networks as graphs
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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
- N1.. NN
- then we can generate couples from this set:
- (N1, N3) (N2, N5)....
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9.1.1 Simple measures on a network
- grade
- maximum number of links
- density
- Clustering Coefficient
- Components
- Diameter
- Assortativity
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Network measures in NetLogo
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Netlogo basic instructions for networks
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Creation
- create-link-with
- create-link-from, create-link-to
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Exploration
- link-neighbors
- in-link-neighbors, out-link-neighbors
- end1, end2, other-end (from links)
- 9.2 The giant component
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Three insights on networks
- 9.3.1 Clue n.1: It's a small world
- 9.3.2 Clue n. 2: The strength of the weak links.
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9.3.3 Clue n. 3: Power laws
- Subtopic 1
- Subtopic 4
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9.4 Preferential attachment
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9.4.1 NetLogo implementation
- Topic
- 9.5 Networks and security