1. Hierarchies and Communities Notes on Linked Ch.16 Nov.10, 2004 Judith Molka-Danielsen

2. 1. Multitasking We can do it. We slow down when we do it. Most complex systems do it. How do complex systems do this with ease? How does the need to multitask affect how the architecture develops? ….most complex systems are modular.

3. 2. How are cells organized? Cells are Modular. Certain modules are responsible for most functions. Cells do multitasking. Analogy – departments and small groups solve specific tasks, multiple tasks. Modularity – is not explained by the Scale Free model. Need something more.

4. Reflection on the scale-free model. Spider Man, who appears in over 1600 comic books is one of the hubs of the Marvel Universe. See, e.g. spiderman-hub.pdf

5. 3. Hierarchical Model

6. Hierarchical Organization of Modularity in Metabolic Networks – Barabasi Hierarchical Organization of Modularity in Metabolic Networks – Barabasi and Supporting MaterialsSupporting Materials

7. -Complex Network Model- a)Scale-free network B)Manifestly modular network c)Scale-free topology with embedded modularity

8. 4. Complexity theory and the modularity of real networks Hierarchical modularity is a property found in most real networks. Alessandro Vespignani – found domain level Intenet maps have a hierarchical organization marked by a scaling of the cluster-coefficient. Visual: www.touchgraph.com/TGGoogleBrowser.html www.touchgraph.com/TGGoogleBrowser.html Future research in complexity theory will be based on the study of networks and the understanding of the concepts of self- organization.

10. http://www.w3.org/2001/11/IsaViz/