签订房屋租赁合同的十大注意事项.pptx

太原房产网 Lecture 5:Network centralitySlides are modified from Lada AdamicMeasures and MetricsKnowing the structure of a network, we can calculate various useful quantities or measures that capture particular features of the network topology.basis of most of such measures are from social network analysisSo far,Degree distribution, Average path length, DensityCentralityDegree, Eigenvector, Katz, PageRank, Hubs, Closeness, Betweenness, ….Several other graph metricsClustering coefficient, Assortativity, Modularity, …Characterizing networks:Who is most central????network centralityWhich nodes are most ‘central’?Definition of ‘central’ varies by context/purposeLocal measure:degreeRelative to rest of network:closeness, betweenness, eigenvector (Bonacich power centrality), Katz, PageRank, …How evenly is centrality distributed among nodes?Centralization, hubs and autthorities, …centrality: who’s important based on their network positionIn each of the following networks, X has higher centrality than Y according toa particular measureindegreeoutdegreebetweennessclosenessOutlineDegree centralityCentralization Betweenness centralityCloseness centralityEigenvector centralityBonacich power centralityKatz centralityPageRankHubs and Authoritiesdegree centrality (undirected)He who has many friends is most important.When is the number of connections the best centrality measure? people who will do favors for you people you can talk to (influence set, information access, …) influence of an article in terms of citations (using in-degree)degree: normalized degree centralitydivide by the max. possible, i.e. (N-1)Prestige in directed social networkswhen ‘prestige’ may be the right wordadmirationinfluencegift-givingtrustdirectionality especially important in instances where ties may not be reciprocated (e.g. dining partners choice network)when ‘prestige’ may not be the right wordgives advice to (can reverse direction)gives orders to (- ” -)lends money to (- ” -)dislikesdistrustsExtensions of un