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Tough Sudoku for 29/January/2008


Choose a number, and place it in the grid above.

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Sudoku Solving Techniques

Submitted by: sudoku lover

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Nothing like fireworks to bring back that sense of wonder.
29/Jan/08 12:27 AM
Good Morning Andrew. I agree!
29/Jan/08 12:44 AM
Interesting jigsaw.
29/Jan/08 2:59 AM
They never fail to amaze.
29/Jan/08 3:08 AM
I'm a sucker for fireworks too. Have a great day/night, everyone!
29/Jan/08 4:26 AM
Gath, any progress on getting the sudoku blog fixed. Really miss it and really need it!!! Thanks.
29/Jan/08 7:35 AM
23:39 to you.
29/Jan/08 7:40 AM
32:03 (?!) mAen! Nice fireworks photo - I bet it's not easy to get a good photo like that... nice work!
29/Jan/08 10:55 AM
I think it is Sue's photo!
29/Jan/08 11:50 AM
My favorite! Red white and purple! ;)
29/Jan/08 12:17 PM
UP 25

1. HP 34 (bc3) forbids b3=578; c3=579, thus a1=8, f3=8, f2=6
2. (a) HP 49 (ef7) forbids e7=56; f7=368
(b) NP 49 (ef7) forbids h7=9; bc7=4
(c) NP 13 (bc7) forbids bc8=3; d7=3; g7=13; h7=1 THUS
g9=1, i9=7
3. TRIPLE 235 (d=35, More...
29/Jan/08 12:34 PM
Thought that was a fairly easy tough, or maybe I made a lucky mistake!! Lovely fireworks, and thanks for the tip HalT!
29/Jan/08 1:41 PM
mAen. 12.07
29/Jan/08 9:01 AM
29/Jan/08 4:15 PM
OOOOOH ARRRRR so pretty.
29/Jan/08 5:04 PM
Joanne, Nice to hear from you again!

In answer to your question, yes, conjugate pairs may be used as either weak or strong.

But after step 6 in your proof I still have possible 9's at h3 and e1 and thus no strong links for 9 in box h2 or column e. Have I missed some way to More...
29/Jan/08 5:10 PM
Joanne, sorry, that last post should have been tagged with comment type Sudoku Technique/Question. Anyway, please have a look at it.
29/Jan/08 5:13 PM
It was an awkward puzzle to do but ended up getting it in a reasonable time...don't think it warranted fireworks but thank you anyway!
29/Jan/08 7:59 PM
Jeff...The hidden triples you found unlock everything!!! Thanks.

I didn't see them, probably because I'm too driven these days to learn more about chains. Although I think I understand them when reading about them, I flat out have trouble deciding if it's a weak or a strong link. More...
30/Jan/08 1:56 PM
Joanne, I still am not very good at locating chains. When I do look for chains (or when I check someone else's) I nearly always fall back to the definition. In other words for a link to be weak it must be impossible for both predicates to be true. And for a link to be strong it must be More...
30/Jan/08 6:05 PM
Jeff, I'll see if your definition works for me. I haven't heard it expressed the same way before. Maybe it will click this time around.

Steve posted in one of his proofs tips that help one spot chain possibilities. I'll see if I can locate his notes. They were helpful. I circle More...
31/Jan/08 6:42 AM
Jeff...Check out Forbidding Chains 102. I think this explains starting points for Forbidding Chains quite well, though I find it easier to read that do. Good luck!
31/Jan/08 6:55 AM
Jeff, regarding Jan. 14 --- I had problems with my grid. I eliminated a candidate that shouldn't have been eliminated, probably beceaus of being sloppy. It worked--though not legitimately.

01/Feb/08 11:39 AM
19/Feb/08 8:55 AM

07/Sep/10 10:43 PM
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