> I mean you’d probably just generate random low descriptive length f(x,y,z), check for a const determinant then poke for invertibility.
That’s true, but for “a ~3 day computer search”, it seems you would have had to be extremely lucky to find a counterexample. Might have had more chance playing the lottery.
Be fun to ask Fable to write a search program to find more counter examples using only early grad theory to guide the search.