u/Visual-Lie-268

Hello people, this is my first time here though I have been doing sudoku for a long time. Easy and Medium were too easy, so I had started with Hard. Been doing the expert level for the last couple of years. (I dont know how do the apps define the Expert level, but I have counted that the board starts with 21-23 givens.) So maybe there are games out there which start with lesser givens. Point is I am not boasting, just trying to give factual information. Now, I have gone through a lot of sites giving advanced sudoku techniques, the X wing variety, but always found them to be pointless. In my experience, they are at best better assumption techniques.

Right now, I am sharing a board in which I reached this status with 10 minutes and after that could not solve it for the next 30 mins. I have always avoided the "make assumptions, check calculations" route. I like to solve my puzzles logically. This board stumped me. And then I found a logic which could actually be formula.

I am here now to take help from other enthusiasts and share my formula for a rigorous testing by others. Before I share the logic, here is the board.

What am I missing?