Factorio – Visualizing construction material dependencies

Those are Directed Acyclic Graphs (DAGs), like used in make, and Snakemake. No mention of that word though. There are some nice libraries and visualization tools for DAGs.

That's a coincidence, that the author only picked recipes that are made without cycles. Other Factorio recipes (e.g. nuclear fuel processing) are cyclic.

There aren't any other ingredient cycles in unmodded Factorio (besides the trivial barrelling/un-barrelling of fluids).

I thought you could go between heavy and light oil cyclically, but I think the recipes I'm thinking of are from UltraCube. The others are a subset of nuclear (Kovarex and reprocessing), so I think you're right.