[throwaway444441]

> A tree with multiple inheritance (sometimes called tangled tree)

By the author's definition, multiple inheritance prohibits cycles. DAGs can be modeled as tree with back edges to non-ancestors. So I'm pretty sure tangled tree = DAG.

> For this example, someone could navigate away from one page, but potentially be linked back to it later down the adventure.

Good point, maybe "tangled tree with back edges to ancestors" is the really correct model for what the author wants. The key point of the visualization is to highlight the deviation from a standard DAG or tree.

[phailhaus]

The author already says that:

> It is technically a directed acyclic graph (DAG)

But DAG's don't have 'roots', they just have nodes. The concept of roots makes it a tangled tree.