A self-loop is a graph relationship whose start node and end node are the same node. In a graph schema, relationships between nodes with the same label can be represented this way. section 2.3.4
Use the Twitter graph-model figure to see FOLLOWS and RETWEETS represented as self-loops for same-label relationships. section 2.3.4
Self-retweet
A Twitter user can retweet one of their own posts. This creates a self-loop and may appear as a single-member weakly connected component. section 6.2.2
Self-loops can distort influence analysis. Before running weighted PageRank on a retweet network, project a new in-memory graph that filters out relationships whose endpoints are the same node. section 6.3 section 6.3.1

