A Puzzle of Clever Connections Nears a Happy End (quantamagazine.org)

I like the terms "cup" and "cap". They correspond to the LaTeX shortcuts \cup and \cap for set union (∪) and set intersection (∩).

As soon as Ronald Graham turned up it wasn't surprisinng that this was related to Ramsey Theory, even as a non-mathematician. Graham's Number is such a wonderfully large thing that introduced me to tetration and up-arrow notation. https://en.wikipedia.org/wiki/Graham%27s_number