Removing equivalent authors in a list
I'm not sure I follow the code, but I would try removing the repeated calls to GetDuplicates:

foreach (var duplicate in authors.GetDuplicates())
{
    for (int j = 0; j &lt; edge.Count; j++)
    {
        for (int k = 0; k &lt; duplicate.Count - 1; k++)
        {
            if (edge[j] == duplicate[k])
            {
                edge[j] = duplicate[k + 1];
            }
        }
    }
}


I've also replaced the calls to ElementAt with use of the indexer, as I think it's clearer.