[GregBuchholz]

Got to love this quote from the "Einstein Problem" page on Wikipedia:

https://en.wikipedia.org/wiki/Einstein_problem

"Depending on the particular definitions of nonperiodicity and the specifications of what sets may qualify as tiles and what types of matching rules are permitted, the problem is either open or solved."

[Infernal]

There's definitely something Douglas Adams-esque about that phrasing.