Hey Greg,
when we made the initial design for Gelly, we discussed having separate
directed and undirected graph types.
We decided to represent undirected graphs by simply adding the
opposite-direction edges, like Apache Giraph does. I'm not sure whether
that was a good idea, but, back then, it
Vasia and I are looking for additional feedback on FLINK-3772. This ticket
[0] and PR [1] provides a set of graph algorithms which compute and store
the degree for vertices and edges.
Degree annotation is a basic component of many algorithms. For example,
PageRank requires the vertex out-degree
