sum of degrees

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sum of all nodes’ degress equals to 2m (each link have 2 end, and is thus counted twice when adding degrees of all nodes together) \[ \sum_V\text{deg}v=2m \]

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modularity

  • Notation
    • \(A_{i,j}\) is entry in adjacency matrix of node i and node j
    • \(\delta(c(i),c(j)\) returns 1 if \(i\) and \(j\) is of the same class, and 0 if \(i\) and \(j\) is of different classes
    • \(m\) - number of links, (\(2m\) is also sum of degrees)
  • definition \[ Q = \frac{1}{2m}\sum_{i,j}(A_{i,j} - \frac{\text{deg} i * \text{deg} j }{2m} )\delta(c(i),c(j)) \]

average degree

devide sum of degrees by number of nodes \[ \bar d_G = \frac{1}{n}\sum_V\text{deg}_Gv \] or equivalently, \[ \bar d_G = \frac{2m}{n} \]

Author: Linfeng He

Created: 2024-04-03 Wed 23:23