Small worlds

```{r setup, include=FALSE} knitr::opts_chunk$set(echo = FALSE) knitr::opts_knit$set(root.dir = './') source("resources/preamble.R") f <- function (x) {formatC(x, format="d", big.mark=',')} bold <- function(x) {paste('{\\textbf{',x,'}}', sep ='')} gray <- function(x) {paste('{\\textcolor{gray}{',x,'}}', sep ='')} wrapify <- function (x) {paste("{", x, "}", sep="")} p <- function (x) {formatC(x, format='f', digits=1, big.mark=',')} source('../class_list.R') set.seed(0121) library(igraph) ```
Human progress is neither automatic nor inevitable... Every step toward the goal of justice requires sacrifice, suffering, and struggle; the tireless exertions and passionate concern of dedicated individuals.
Martin Luther King, Jr.
## Housekeeping > - Tech policy > - Designated reminder > - Proposed structure for class > - Semi-"flipped" class ## Questions from the homework >- Edgelists >- Matrices >- Graphs # Why is the network perspective so important? ## Power failure example ## Complex systems are all around us > - Interdependent > - Non-linear > - Unpredictable, even when individuals are understood ## Segregation Example > - Link to this example is on the wiki > - Go through this with a partner > - Discuss in small groups > - Discuss as a class ## Emergence > - How does individual behavior aggregate? > - When is this simple? When is it complicated? (TPS) > - Fire example > - Boids example ## Interdependence and Structure > - If components are interdependent, then how they are connected matters > - Both for individuals and for the system > - What are some examples of this? (TPS) ## Structure of networks > - What do real social networks look like? > - What is clustering? > - What is a random graph? ## Random Graph ```{r} G = erdos.renyi.game(100, .3) V(G)$size = 8 l <- layout_with_graphopt(G) plot(G, directed = T, layout = l, vertex.label='') ``` ## Actual social network - Faculty friendship network ```{r} library(igraphdata) data("UKfaculty") l <- layout_with_graphopt(UKfaculty) V(UKfaculty)$size = 8 V(UKfaculty)$label = '' plot(UKfaculty, edge.arrow.size=.3, edge.curved=.1, layout = l) ``` ## Other insights and ideas from Six Degrees? ## Assignments > - Read Chapter 3 of Six Degrees # Six Degrees of Wikipedia ## Concepts from reading > - Structure and agency > - Clustering > - Path lengths > - Distance ## Putting it together > - What does "Six Degrees" refer to? > - What is the puzzle? > - What is the solution? ## Milgram Experiment >- What was he trying to do? >- Did you find the results surprising? >- Do you think that technology has changed this today? In what ways >- What do you think the distance is of the Purdue network? ## How is knowledge connected? > - Six Degrees of Wikipedia > - Can be done in pairs, turn in with both names on it## Assignment > - Find someone with HI driver's license