The New Sudoku Players' Forum

[asdfgh]

Hello again guys. I'm studying some advanced technics but I still have problems to find them. Can you show me what is the next move, please:

..9.2..5.
5...9..4.
4.713598.
17.659.3.
...2.1579
29537.16.
.529.7.13
731.62.95
9..51372.

Thank you.

[JasonLion]

I see a remote pair on 48: R6C9 - R6C6 - R5C5 - R7C5 - R8C4 - R8C7 so R4C7 can't contain 4 or 8.

That plus a few simpler steps and the puzzle is solved

[Leren]

Code: Select all

*--------------------------------------------------------------*
| 368   168   9      | 478   2     468    | 36    5     17     |
| 5     1268  368    | 78    9     68     | 236   4     17     |
| 4     26    7      | 1     3     5      | 9     8     26     |
|--------------------+--------------------+--------------------|
| 1     7    a48     | 6     5     9      | 2-8   3     248    |
| 368  b468  b3468   | 2    c48    1      | 5     7     9      |
| 2     9     5      | 3     7     48     | 1     6     48     |
|--------------------+--------------------+--------------------|
| 68    5     2      | 9    d48    7      | 468   1     3      |
| 7     3     1      |e48    6     2      |f48    9     5      |
| 9     468   468    | 5     1     3      | 7     2     68     |
*--------------------------------------------------------------*

You can solve the puzzle from this position in 1 move plus follow on singles.

From your clues a few basic moves (2 lots of pointing pairs and a locked triple) will get you to here, which I assume you are familiar with - if not let me know and I'll explain further.

Follow the cells in the order abcdef. Assume r4c3 is not 8. Then it must be 4, so both r5c23 can't be 4, so r5c5 is 4 (only 3 4's on Row 5), so r7c4 is not 4 so it's 8. So r8c4 is not an 8, so r8c7 is 8 (only 2 8's in Row 8).

If you start by assuming that r8c7 is not an 8 then follow the cells in the reverse order fedcba you'll find that r4c3 is 8.

So at least one of r4c3 or r8c7 must be 8. They might both be 8 but they can't both be not 8. Since r5c7 can see both of these cells it can't be 8. So it's 2, and the puzzle solves easily from there with singles.

This slightly fancy move is called a W Wing with transport (The W Wing is cells abcd and the transport is the extra cells e and f).

Here is a link to a site that discusses W Wings http://hodoku.sourceforge.net/en/tech_wings.php#w

Leren