[pyre]

> Each log corresponds to a subgraph of the full DAG

I don't have the time to keep up this conversation, but this assertion is wrong. It is not a subgraph. It is a history of the values that the pointer was pointing to (e.g. "Pointer <branch_name> changed from pointing to value AAA to value BBB due to action XXX"). That is basically what all of those entries are. 'AAA' and 'BBB' maybe be in completely unconnected sections of the DAG.

If you create a new repository and add a couple of commits, then yes the reflog files will look like a history, but only because the branch pointer has traversed the DAG from start to end with no deviations.

For example you can have a DAG like this:

   A - B - C - D - E

   X - Y - Z

If you change the branch pointer to move from B to Z, this is not a subgraph. Well, I guess technically you could call it sgraph of the history of the branch pointer, but it in no way corresponds to the DAG other than that all of the pointer values exist within the DAG. For example the following operations:

  git clone
  git reset --hard Z
  git reset --hard X

Would create a graph like this (assuming that master pointed to E when you cloned):

  E - Z - X

Notice that this really don't correspond to the DAG other than the fact that those objects exist in the DAG.

Note:

- All of this information is only contained within the .git/logs files. None of it is stored in the objects themselves.