Happy New Year, all,

I'm interested in comments relating to the discussion of what I am calling "almost-locked ranges" at

http://www.stolaf.edu/people/hansonr/sudoku/explain.htm#almostrange

These relate to recent discussions here as well as some of the more complicated fish analyses.

Have these been popularized? (I suspect so.) Pointers to where they are discussed within our outside this forum would be appreciated. I may want to add a few of those links to that explanation page.

I realized that I use them extensively myself when solving puzzles by hand, and since they were recently discussed here in a slightly different context, I incorporated them into the Sudoku Assistant today. The results for the impossible520 set (given at that link above) are really quite impressive. Obviously almost-locked sets are everywhere and whether by that name or not are very powerful devices.

A preliminary set of examples, some of which are quite simple, and some of which are more challenging to figure out by hand can be found at:

http://www.stolaf.edu/people/hansonr/sudoku/ex_A2.htm?n=20&search=ALS-B

Thanks in advance,

Bob Hanson