I was introduced to sudoku a couple of months ago by my cousin and her husband. In their San Diego newspaper there were published what I think are garden variety sudoku rated from one to five stars in difficulty. These are 9x9 grids with 9 3x3 sub-grids, and every row and column of 9 squares must contain the digits 1-9. Each 3x3 sub-grid must also contain all nine digits 1-9. I've taken to doing the puzzles published in my local paper, the Oakland Tribune. They appear to be the same type as those I saw in San Diego, rated from one to five stars in difficulty. I'm wondering how they determine the difficulty of these puzzles. My cousin's husband said that some of the puzzles are only solvable if you do a "what if" scenario, and we gave up on the puzzle we were trying, a five star. I'm not willing to resort to "what if" tactics. I've solved some 5 star puzzles pretty easily and been stumped by a couple of 4 star puzzles. I had to wonder if they misjudged the difficulty.