View previous topic :: View next topic |
Author |
Message |
Glassman
Joined: 21 Oct 2005 Posts: 50 Location: England
|
Posted: Sun May 27, 2007 9:21 pm Post subject: Stuart puzzle May 25 diabolical — spoiler warning |
|
|
Code: |
+---------------+------------+---------------+
| 3 48 1578 | 67 2 14 | 49 146 5689 |
| 1247 6 157 | 9 147 8 | 3 14 25 |
| 124 9 18 | 5 146 3 | 24 7 268 |
+---------------+------------+---------------+
| 8 127 3 | 67 167 129 | 5 29 4 |
| 9 12 4 | 8 5 12 | 6 3 7 |
| 5 27 6 | 3 47 249 | 8 29 1 |
+---------------+------------+---------------+
| 146 3 19 | 2 8 7 | 149 5 69 |
| 17 5 2 | 4 9 6 | 17 8 3 |
| 467 48 789 | 1 3 5 | 2479 46 269 |
+---------------+------------+---------------+
|
Play this puzzle online at the Daily Sudoku site
I'm really stuck on this. The hint is to eliminate the 6 at r1c4, but I can't see how.
Help
Glassman |
|
Back to top |
|
|
keith
Joined: 19 Sep 2005 Posts: 3355 Location: near Detroit, Michigan, USA
|
Posted: Sun May 27, 2007 9:39 pm Post subject: |
|
|
Glassman,
At the risk of irritating you, the Type 3 UR in R46C68 says R5C6 is <2>.
Otherwise, an XY-wing 18-48-14 takes out <1> from R1C3 an R3C5.
Then, there is another XY-wing, and an X-wing ...
Neat puzzle!
But, I do not see how to complete the puzzle without a chain ...
Keith |
|
Back to top |
|
|
Mogulmeister
Joined: 03 May 2007 Posts: 1151
|
Posted: Sun May 27, 2007 10:13 pm Post subject: |
|
|
Glassman,
I don't see it straight away either - I do see an XY wing though. |
|
Back to top |
|
|
Mogulmeister
Joined: 03 May 2007 Posts: 1151
|
Posted: Sun May 27, 2007 10:41 pm Post subject: |
|
|
Eureka !
Take the XY Wing that Keith identified - crucially by removing the 1 from r3c5 this reduces that square to a <46> bivalue.
Now we can eliminate that 6 that is troubling you:
ALS - Set A is r3c5 <46>.
Set B is r4c4 <67> and r6c5 <47>
Locked common is 4. The 6 in r1c4 can see both 6's in A & B and is thus eliminated.
NB these cells will also make up an XY chain - pincers at r3c5 and r4c4. |
|
Back to top |
|
|
Mogulmeister
Joined: 03 May 2007 Posts: 1151
|
Posted: Sun May 27, 2007 11:10 pm Post subject: |
|
|
All this having been said there is a way to go to complete the puzzle......... |
|
Back to top |
|
|
Glassman
Joined: 21 Oct 2005 Posts: 50 Location: England
|
Posted: Sun May 27, 2007 11:33 pm Post subject: |
|
|
Keith — I got side-tracked when I realised that your xy-wing eliminated the 1s at r2c1 and r2c3. That 57 was too tempting a prize not to be of use.
Mogulmeister — I prefer yours as a simple xy-wing — I struggle with ALSs.
Oh, and Keith, thank you for your diplomacy. However, has Andrew Stuart ever said that all his puzzles have a unique solution? ... or that he never makes a mistake? And, if so, would you believe him?
Glassman |
|
Back to top |
|
|
Mogulmeister
Joined: 03 May 2007 Posts: 1151
|
Posted: Sun May 27, 2007 11:47 pm Post subject: |
|
|
I put in the ALS because it got rid of your 6 but if x-y chain works as well so be it.
Personally, I would definitely always trust Andrew Stuart - he worked with and has now succeeded Michael Mepham(RIP) whose Sudoku puzzles always have one solution.
I think he does excellent work. |
|
Back to top |
|
|
|