Can't seem to solve this one

Advanced methods and approaches for solving Sudoku puzzles

Can't seem to solve this one

Would be most grateful if someone could give me a clue --- I guess I am missing something obvious. I've been looking at it for a week and it doesn't get any better!

x4x x81 xxx
2xx 4xx 65x
xx3 xx5 xx4

91x 5xx 3xx
xx2 1xx 9xx
3x4 xxx 517

6xx 85x 4xx
x37 xx9 xx5
xxx 31x x6x

Have found X-wing's in 1's and 3's and a various pairs and triples but so far can't see a next step.

Be most grateful if anyone can be bothered.....

George
(georgers1@gmail.com)
georgers

Posts: 13
Joined: 04 June 2005

Naked pair in block 4, then row 5, then column 1. Then a few block/column/row interactions and it's done.

Simes
simes

Posts: 324
Joined: 11 March 2005
Location: UK

Can't seem to solve this one

Err ... thank you. I have 2 naked pairs in Block 4 ( 5,7 and 6,8). I also have a naked pair in Column 1 (5,7 again). There's a naked pair in Block 3 also (1,8). And a naked pair in Row 3 (1,8 again).

But it's where I go from there that I haven't found --- must be missing something totally obvious or I've gone wrong somewhere. Could you spell out the next step?

George
(georgers1@gmail.com)
georgers

Posts: 13
Joined: 04 June 2005

okley dokley...

Sorry... looked deeper, those pairs don't help much!

block 8 column 6, look at digit 7 and make an elimination in r2c6

simes
simes

Posts: 324
Joined: 11 March 2005
Location: UK

Can't seem to solve this one

Thanks very much ---- and it only took you 10 minutes, gnash, gnash!

All best!
georgers

Posts: 13
Joined: 04 June 2005

That particular type of clue (that simes supplied), though elementary, is easy to overlook: In a given box, a particular value can be in one of only two cells, and those two cells are in a single row, or a single column, therefore excluding that value from all other cells in that row, or column, in the two other boxes as well. This situation is so common, so useful, but so (relatively) opaque, that I've taken to entering a distinct pencil mark for it. Does it have a name? If not, it should.
Doyle

Posts: 61
Joined: 11 July 2005

Yes, you're referring to restricted candidates.
george-no1

Posts: 150
Joined: 20 May 2005