The New Sudoku Players' Forum

[justin]

Hello,

I'm doing the www.sudokuaddict.com "Very Hard" puzzle #8 .

Puzzle and solution can be found here:

http://www.sudokuaddict.com/puzzles/1-50/8.asp

I'm stuck finding the next "logical" ("non-guessing") move or even candidate elimination. Given more the 1/2 cells are filled, I must be missing something. Anyone want to throw me a bone on what I've obviously missed and why, greatly appreciated.

4x3/16x/xxx
x6x/x73/x14
718/4xx/635
8x7/6xx/x91
x36/xxx/x5x
x4x/xx7/x62
675/xx4/1x9
3x4/951/x76
xxx/7x6/543

My candidates for the X's are in parenthesis:

4(259)3/16(58)/(2789)(28)(78)
(259)6(29)/(58)73/(289)14
718/4(29)(29)/635
8(25)7/6(34)(25)/(34)91
(129)36/(28)(1248)(289)/(478)5(78)
(159)4(19)/(358)(1389)7/(38)62
675/(238)(238)4/1(28)9
3(28)4/951/(28)76
(129)(289)(129)/7(28)6/543

At some point I whittled the (2789) row 1/ col 7 down to just (79), but I can't see how I did that now. Without guessing. Maybe it's time to go eat something.

Thanks!

[SteveF]

Look for some naked pairs in rows 3 and 4. Then you need to look for an x-wing.

[justin]

Look for some naked pairs in rows 3 and 4. Then you need to look for an x-wing.

Thanks Steve.

I think I've handeld the naked pairs appropirately. I've been trying to see an X-Wing, but I finally noticed all those (28)'s link in such a manner that (R,C) (1,8) & (8,2) are always opposite, and thus cell (1,2) can't have "2" as a candidate. Which forces some other things ...

Thanks.