The New Sudoku Players' Forum

[brianp]

Can't remember where this one came from. Probably the Times. I've been working on it for ages. I've re-started three times. I've given it to a friend and she solved it by making a guess.

Original grid
1,,2,7,,9
,9,,4,,7,
,,,8,9,,,
,2,,9,,5,
,,9,,,2,,
,3,,7,,4,
,,,1,4,,,
,4,,3,,8,
8,,9,6,,7

Then I got as far as this before getting stuck. I was quite pleased to find block 8 solved so quickly, but then it all ground to a halt

1,42,7,,9
,9,,4,,7,
,,,8,9,,4
,2,,9,75,
,,9,,,2,,
,3,,7294,
,,,184,9,
94,735,8,
8,,9264,7

Any hints or tips please?

[simes]

I guess you're stuck at the XWing? It's rows 5 and 9, columns 2 and 8 for 1.

S

[MCC]

simes, I don't see a x-wing in 1's at those positions.

Row 5 has five cells with 1 as a candidate.
Row 9 has three cells with 1 as a candidate.
Column 2 has two cells with 1 as a candidate.
Column 8 has three cells with 1 as a candidate.

So if you use rows or columns you cannot form a x-wing.

[PaulIQ164]

And if it's a regular weekday/Saturday puzzle, you shouldn't need an X-Wing.

[MCC]

Ok simes, I see where you got the x-wing, but first of all you have to place the 2 in r3c8, it's the only place for a 2 in column 8.

That leaves two 1's in columns 2 and in 8.

You can therefore eliminate several 1's from rows 5 and 9.

[simes]

And if it's a regular weekday/Saturday puzzle, you shouldn't need an X-Wing.

but we don't know where it came from with any certainty, all we have is a "probably."

So how did you solve it?

S

[PaulIQ164]

Well, I didn't. And in fact, the Susser agrees you need an X-Wing. So I guess it is a Sunday Times puzzle. I thought I could check by inputting the first five digits in the solutions page, and seeing which of the papers I had to select for it to work, but apparently you can select either the Times or the Sunday Times regardless of which paper you're entering a puzzle from.

[simes]

Well, I didn't.

Never let a little ignorance get in the way eh?

[brianp]

Thanks for all the comments.
Having got back home and dug out my previous attempts, I see that one of them (the first one) already sports a 2 in r3c8, which ties up. I never thought of a transverse x-wing, but it's obvious they must exist as one could rotate the puzzle through 90 degrees.
Right then. Onwards from here.
Incidentally, I think it most likely to be a Sunday Times puzzle, probably late August or early September.
Thanks again
Brianp

[Pat]

the Susser agrees you need an X-Wing.

So I guess it is a Sunday Times puzzle.

The Sunday Times #11 (2005.Oct.9)

- Pat