help - very hard

Advanced methods and approaches for solving Sudoku puzzles

help - very hard

Postby BadCujo » Fri Jun 24, 2005 3:04 pm

I have gotten to this point but am not seeing any way to move further without T&E

792 **5 *63
*1* **7 5*9
*5* *39 *7*

*8* *** 352
*** *5* ***
5*1 *** *4*

*7* 968 ***
8** 5** *9*
*4* *** 8**
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Postby Animator » Fri Jun 24, 2005 3:40 pm

You should take a really good look at row 9. And after that you should ook at column 1. (After removing some candidates that is)
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Postby BadCujo » Fri Jun 24, 2005 4:04 pm

I still don't see it
I'm showing the following for R9

{12369} {4} {3569} {1237} {127} {123} {8} {123} {1567}
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Postby Karyobin » Fri Jun 24, 2005 4:21 pm

Well exactly. Not having done it myself, and therefore assuming your working is correct: why don't you discount all references to candidates 1,2,3 and 7 in cells 1,3 and 9? Haven't you spotted the quad relationship in cells 4,5,6 and 8? No problem if you haven't, but I suggest you read some of the method/technique files belonging to simes or angus.

Good luck with the rest of it.
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Postby BadCujo » Fri Jun 24, 2005 6:00 pm

Thanks...... I guess I was not expecting Quads from Pappocom. I think I understand it now. I hope at some point I can spot them as easily as pairs and triples.
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Postby Pappocom » Fri Jun 24, 2005 7:30 pm

Quads are not necessary for solving Pappocom puzzles. If they exist and you can find 'em, then make use of them, by all means - but somewhere there will be a simpler way.

- Wayne
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Postby scrose » Fri Jun 24, 2005 7:51 pm

It does look like row 9 is the key to solving this puzzle. It's a little amusing that the {1237} quad is easier to spot than the {569} triple.
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Postby Pappocom » Fri Jun 24, 2005 8:04 pm

Actually, I was a bit hasty in my last reply. I should have said that Quads are not necessary to solve this puzzle.

It is possible to have a Pappocom puzzle where you must use Quads in order to make progress - but only in Very Hard puzzles.

- Wayne
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