At around 43:00, I mention the graph having forks and joins, but it only has forks in Lindsey's model. If I add the machinery I have stolen from [Concurrent Revisions](research.microsoft.com/en-us/projects/revisions/) to the Par monad _then_ I get joins.
At 16:23 I mention you need the ability to compare for equality. You only need that power when the cell participates in a cycle. Effectively every edge into a node that can't be compared for equality is a stratifying edge.
At around 43:00, I mention the graph having forks and joins, but it only has forks in Lindsey's model. If I add the machinery I have stolen from [Concurrent Revisions](research.microsoft.com/en-us/projects/revisions/) to the Par monad _then_ I get joins.
At 16:23 I mention you need the ability to compare for equality. You only need that power when the cell participates in a cycle. Effectively every edge into a node that can't be compared for equality is a stratifying edge.