Phistomefel's Ring: An Intuitive Explanation
NOTE: Post was added in April 2022 and backdated to reflect video publication date
I've become obsessed with weird sudoku stuff after following Cracking the Cryptic. Find their channel here: https://www.youtube.com/c/CrackingTheCryptic
Here's an intuitive explanation of "Set Equivalence Theory", and in particular Phistomefel's Ring, that hopefully any sudoku solver of any level of experience will be able to follow.