## Did I need to guess?

Everything about Sudoku that doesn't fit in one of the other sections

### Did I need to guess?

So I guess r9c7=7 and the puzzle immediately solves.

Failing a guessing game, I don't see how else to proceed.

If you see something (tso - please name the exact cells and values involved) that leads to elimination of a pencilmark, etc., please let me know.

Thanks! Mac

Solution So Far
56- --1 --8
--- 5-- 6--
--- -62 57-
-9- 2-5 18-
--4 -1- 3--
--8 3-9 -2-
-76 98- ---
--5 -2- 8--
8-- 15- --3
Pencilmarks So Far
- - 279 47 39 - 249 349 -
12479 1248 1279 - 39 478 - 1349 1249
1349 1348 139 48 - - - - 149
367 - 37 - 47 - - - 467
27 25 - 68 - 68 - 59 579
167 15 - - 47 - 47 - 4567
1234 - - - - 34 24 145 1245
1349 134 - 467 - 3467 - 1469 1479
- 24 29 - - 467 2479 469 -
QBasicMac

Posts: 441
Joined: 13 July 2005

You can start by making some more eliminations in row 6.
Anette

Posts: 55
Joined: 09 June 2005

...and then I also did not get very much farther. I managed to eliminate some 1's from box 1, but got as stuck as you.

Sorry.
Anette

Posts: 55
Joined: 09 June 2005

Hi, Anette,

Those were the kind of careless oversights I was hoping to find. Thanks for pointing them out.

Now it appears even more hopeless. Would this be a case where guessing is an acceptable technique?

Mac
QBasicMac

Posts: 441
Joined: 13 July 2005

I tried to solve this with a program with limited solving techniques.
It didn't find any other cell.

It helped me prove indirectly that r9c7 must be 7 otherwise there remains no solution.
evert

Posts: 186
Joined: 26 August 2005

QBasicMac wrote:Now it appears even more hopeless. Would this be a case where guessing is an acceptable technique?

With only Pappocom-approved moves, the candidates can be reduced only a bit further before more sophisticated logical methods are needed. Some of these methods are discussed on this forum at http://forum.enjoysudoku.com/viewtopic.php?t=1344
and the puzzle is also solved with step-by-step explanations by the online solver at http://act365.com/sudoku/ (with the "guessing" mode turned off).
r.e.s.

Posts: 337
Joined: 31 August 2005