## help - very hard

Advanced methods and approaches for solving Sudoku puzzles

### help - very hard

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**

Posts: 19
Joined: 07 June 2005

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)
Animator

Posts: 469
Joined: 08 April 2005

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

{12369} {4} {3569} {1237} {127} {123} {8} {123} {1567}

Posts: 19
Joined: 07 June 2005

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.
Karyobin

Posts: 396
Joined: 18 June 2005

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.

Posts: 19
Joined: 07 June 2005

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
Pappocom

Posts: 599
Joined: 05 March 2005

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.
scrose

Posts: 322
Joined: 31 May 2005

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
Pappocom

Posts: 599
Joined: 05 March 2005