[gwf]

Not-so-humble-brag: I am the first author in the first paper referenced in the linked PDF. I came up with the original PSPACE-completeness proof as well as the model of computation from which this is all based. So, yeah, it's kind of awesome to read this 22 years later while browsing HN.

[klyrs]

Thank you! Only, I didn't get much past the first page tonight; I built the "dad's puzzle" out of legos and solved it instead...

Well, I accomplished the goal, but far from minimally so.