I've come to the conclusion that the LATimes does _not_ use a program to rate the Sudoku's. In the past several days, there have been two Moderate's: one was easily solved by my Level 1 (k=1&8), while the other wasn't solved by Level 3 (considering k=1,2,3, as well as implicitly k=8,7,6). This last Moderate should be relabeled at least "Tough", or worse. It also appears that the utility of the higher levels of k is very limited. I've only found 1 or 2 Sudokus where k=3/6 helped. Also, the "k rule" (pigeonhole rule) doesn't capture the power of some very useful rules, which relatively unskilled Sudoku people (like myself) use. I'm still trying to formalize a simple characterization of non-lookahead, non-backtracking strategies for Sudoku.