Review for Quiz

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Quiz #2 review:

Be sure you understand the following concepts, computations, derivations, and operations. Note that definitions of all terms are according to our textbook, ESNAP. (And everything is in the book!) You don't need to know all the detail in the book, and you will not be tested on your ability to use Pajek. Just understand the basic concepts and computations:

  • The "symmetrize" operation
  • Computing the number of links in a simple network—directed, or undirected—containing N nodes
  • Computing density of a network
  • Walks and semiwalks
  • Paths and semipaths
  • Cycles and semicycles
  • Note: "semi" always means: you can take "one ways" the wrong direction. Note that adding "semi" doesn't change anything for undirected networks.
  • Strong and weak components (strong components "hang together" the most - there's a path connecting every pair of nodes and it's as big as it can be - "maximal". for weak components substitute "semipath" for "path". For undirected networks the two concepts are the same.)
  • Degree (indegree, outdegree for directed networks) and degree distribution
  • K-cores and their components (how to find the 3-core? delete all nodes with degree less than 3, then repeat until you have only degree 3 nodes remaining. Ditto for the other cores)
  • Signed graphs (contain positive and negative lines)
  • Balanced (semi)cycles (contain an even number of negative lines, i.e. 0,2,4,6...) and clusterable (semi)cycles (contain an even number of negative lines i.e. 0,2,4,6.., or an odd number of lines starting with 3,5,7, etc. - the only condition: they don't contain just one negative)
  • Balanced graphs (no unbalanced cycles - every (semi)cycle has an even number of negatives)
  • Clusterable graphs (no unclusterable cycles)
  • Two mode networks, and affiliation networks
  • Deriving a one-mode valued network from a two-mode network
  • Contour lines and islands
  • (don't worry about all the other detail in the Affiliation network chapter 5; just know the basics)

Hint: review the questions at the ends of ESNAP chapters 3, 4, and 5 (Sections 3.8, 4.7, 5.8). Answers are provided at the end of each chapter. Make sure you understand them!