I am talking about cube theory. Solving it isn’t that hard unless you want to be super efficient. But formalizing it in way you can then reason about seems very hard to me.
https://www.ryanheise.com/cube/theory.html https://www.ryanheise.com/cube/fundamental_techniques.html
From there you should have enough of an understanding to start Googling things, playing with a cube, and Learning the Heise method: https://www.ryanheise.com/cube/heise_method.html