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I have tried this puzzle twice and get to the same point. Can't get any further. Can anyone help? Thx.

Code: Select all

128  7    126  4    569  3    569  68   258
249  249  3    126  8    15   7    46   245
248  5    246  26   69   7    3469 1    2348
5    24   24   3    1    6    8    7    9
6    1    9    5    7    8    34   2    34
7    3    8    9    2    4    1    5    6
134  6    145  8    35   2    45   9    7
39   89   7    16   4    15   2    368  58
234  248  245  7    356  9    456  3468 1


Sorry for the jumble of numbers -- I pasted it in from Excel and it didn't take the spacing.

I fixed up the formatting for you. The key step is to use a code tag around the fixed format text.

I see a unique rectangle.

Wow! Is it r2c4, r2c6, r8c4, r8c6? In which case r2c4 must be 2?
I've never used that before; if I've got it right, I can see that it's very effective.

No, I don't think I have identified the rectangle. May need some assistance here.

A type 4 in R35C79 on 34.

There's also a pair of X-Wings present. One is very productive, the other isn't.

Is the effect of the unique rectangle, type 4, that because the 3 MUST be in r3c7 or r3c9, then the 4 can be in neither? Sorry to be thick about this, but I've not run into these before and I'm eager to pick up this technique.

Also, daj95376, point out the productive X-wing and I'll see if I can find the other.

Look at the digit 6 in rows 2 & 8.

Got the X-Wing; thanks. Still confused about the rectangle.

QiGuy wrote:Is the effect of the unique rectangle, type 4, that because the 3 MUST be in r3c7 or r3c9, then the 4 can be in neither? Sorry to be thick about this, but I've not run into these before and I'm eager to pick up this technique.

If digit 4 is ultimately placed in neither r3c1 nor r3c3, then r35c79 contains a deadly pattern -- in this case, candidates <34> in all four UR cells. The deadly pattern cannot occur in a puzzle with a unique solution. Therefore, ultimately either r3c1=4 or r3c3=4. All digit 4 candidates that see both these cells may be eliminated.

Nice! Thanks very much -- got it!