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Is it a valid move to observe that if r5c4 is 1 then there is no longer a unique solution because there would be a 25 option in r4c25 and r5c25?

Hence r5c4 is 2?

+-----------+-----------+--- ...

Pretty early on:
XY wing 247 on r1c2, eliminates 7 from r3c4 and r3c5

+-----------------+-----------------+--------------+
| 5 24 467 | 47 9 1467 | 27 3 8 |
| 8 2349 34679 ...

From one of the newspapers a week or so ago

+--------------+-------------+--------------+
| 19 3 59 | 7 6 8 | 4 25 125 |
| 146 8 46 | 2 5 9 | 36 7 136 |
| 7 56 2 ...

It's a Time Zone problem.

The title of the Post does not match the puzzle which is being solved.

The Aug 26 puzzle is a Hard, and can be solved with Basics, per Earl.

The Aug 25 puzzle, on th ...

It took me multiple steps, but here goes with my answer:

1-2-8 XY-wing pivoted on r9c1 eliminates 1 from r3c4:

+-------------------+---------------+-------------------+
| 7 1269 5 | ...

Is this an allowable step?

Starting from Hugh's grid, if r3c5 is 4, then we have a chain of cells with 57 as the candidates, viz r1c4,r1c5,r7c5,r7c7,r9c7,r9c4,r1c4 (again) so the puzzle would have ...

From exactly the same point as Clement there is a 157 XY wing pivoted on r9c6 which eliminates the 5 from r6c4, also making r6c5<>3 leading to the same outcome.

Another +1 from New Zild

As an occasional visitor, but ine who thoroughly enjoys the puzzles, I too would like to offer Marty my best wishes for a speedy recovery

+---------------+---------------+------------+
| 4 256 3 | 7 258 58 | 1 9 268 |
| 289 29 7 | 6 2389 138 | 4 5 238 |
| 2589 2569 1 | 23 23589 4 | 38 368 7 |
+----- ...

Fastest puzzle in a while?

The XY wing identified by Hugh is revealed after only one basic move from the starting position:

+----------------+------------------+-----------------+
| 127 8 2 ...

As an alternative, from the same starting point, there is an XY chain starting at r1c9 which eliminates the 5 from r7c9 thus:

If r1c9 = 5 then r7c9<>5 AND
If r1c9 = 4 then r1c3=2 so r9c3=9 s ...

I think you raise an interesting point, Robert, that one looks to use techniques that match the classification.

I arrived at a similar result starting with simpler techniques.

From Clement's gri ...

+----------------+------------+-----------+
| 8 149 49 | 5 2 7 | 46 1469 3 |
| 1259 12459 249 | 6 134 #34 | 8 149 7 |
| 7 6 3 | *48 148 9 | 2 14 5 |
+--------------- ...

+------------+---------+-----------+
| 467 46 9 | 47 8 5 | 1 2 3 |
| 8 2 37 | 37 9 1 | 46 46 5 |
| 1 5 34 | 34 2 6 | 8 7 9 |
+------------+---------+-----------+
| 9 *4 ...

+-------------+--------------+-------------+
| 269 4 58 | 3 256 25 | 1 7 89 |
| 679 679 58 | 567 4 1 | 39 389 2 |
| 27 1 3 | 27 8 9 | 4 5 6 |
+------------- ...

+----------+-------------+----------+
| 8 2 1 | 5 6 47 | 9 3 47 |
| 7 6 9 | 1 38 34 | 5 2 48 |
| 4 5 3 | 2789 89 279 | 78 1 6 |
+----------+-------------+----------+
| 5 ...

+----------+-------------+----------+
| 8 2 1 | 5 6 47 | 9 3 47 |
| 7 6 9 | 1 38 34 | 5 2 48 |
| 4 5 3 | 2789 89 279 | 78 1 6 |
+----------+-------------+----------+
| 5 ...

You are quite right George, whilst going through the basic moves some more complex things (like X-wings on 5 and Cool

, but on closer examination these moves are not required, and basic stuff will get yo ...

Thanks Marty, voice of reason again. Smile

Interesting that the 5 from r1c8 was eliminated by the wing I spotted, and yet you saw a better more basic move that gives the same result.

I like to t ...