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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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 Posted: Sat Jan 23, 2010 4:16 pm Post subject: Jan 23 VH |
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Looks tougher than it really is. The old reliable will do it.
Solution 235 xy-wing
Early Earl, a bit tardy |
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Ema Nymton
Joined: 17 Apr 2009
Posts: 89
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| Posted: Sat Jan 23, 2010 5:48 pm Post subject: |
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For the rest of us, the word is , stumped.
So far:
| Code: |
+----------------+------------------+------------+
| 468 7 9 | 568 1 458 | 2 58 3 |
| 128 123 28 | 7 9 2358 | 4 58 6 |
| 5 2346 268 | 2368 23468 2348 | 1 9 7 |
+----------------+------------------+------------+
| 7 5 4 | 123 23 9 | 8 6 12 |
| 9 26 3 | 1268 268 7 | 5 12 4 |
| 26 8 1 | 4 256 25* | 7 3 9 |
+----------------+------------------+------------+
| 12468 9 268 | 128 248 1248 | 3 7 5 |
| 1248 124 7 | 12358 23458 6 | 9 1248 128 |
| 3 124 5 | 9 7 1248 | 6 1248 128 |
+----------------+------------------+------------+
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DRAW/PLAY gives hint that R6C6 should be '5'. Why?
Ema Nymton
Seeking answers.
~@:o?
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Jan 23, 2010 6:08 pm Post subject: |
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| Code: |
+----------------+-----------------+-----------+
| 468 7 9 | 568 1 458 | 2 58 3 |
| 128 123 28 | 7 9 2358 | 4 58 6 |
| 5 2346 268 | 2368 23468 2348 | 1 9 7 |
+----------------+-----------------+-----------+
| 7 5 4 | 123 23 9 | 8 6 12 |
| 9 26 3 | 1268 268 7 | 5 12 4 |
| 26 8 1 | 4 256 25 | 7 3 9 |
+----------------+-----------------+-----------+
| 12468 9 268 | 128 248 1248 | 3 7 5 |
| 1248 124 7 | 35 35 6 | 9 124 128 |
| 3 124 5 | 9 7 1248 | 6 124 128 |
+----------------+-----------------+-----------+
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Play this puzzle online at the Daily Sudoku site
Ema, this a the grid after cleaning up a little based on the 58 pair in box 3 and the 1248 quad in row 8.
There is an XY-Wing pivoted in r4c5. The pivot is 23 and the pincers cells are the 25 and 35 in r6c6 and r8c5. The pincers of 5 take out the 5 from r6c5, leaving r6c6 as the only 5 in the box and row. |
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Ema Nymton
Joined: 17 Apr 2009
Posts: 89
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| Posted: Sat Jan 23, 2010 6:45 pm Post subject: |
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| Marty R. wrote: | [code]
There is an XY-Wing pivoted in r4c5. The pivot is 23 and the pincers cells are the 25 and 35 in r6c6 and r8c5. The pincers of 5 take out the 5 from r6c5, leaving r6c6 as the only 5 in the box and row. |
Finally, _this_ makes sense! Your explanation works wonders for me. I was stumped and frustrated. Now I can go forward.
Thank you.
Ema Nymton
~@:o)
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roaa
Joined: 18 Apr 2009
Posts: 112
Location: Sweden
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| Posted: Sat Jan 23, 2010 7:53 pm Post subject: VH Jan 23 |
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I had to find the hidden pair 35 before the xy-wing, which took much longer time than finding the old reliable. Or have I missed something?
In any case, a good one! |
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lpj004
Joined: 25 Nov 2008
Posts: 2
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| Posted: Sat Jan 23, 2010 8:01 pm Post subject: |
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This puzzle didn't seem to be a VH. Only basic moves were needed.
At this stage, the "Grade" button showed "very hard", though clearly it isn't. Enter the 6 in r1c1 and grade shows "easy."
+-------------+------------------+------------+
| 46 7 9 | 568 1 458 | 2 58 3 |
| 12 13 28 | 7 23589 2358 | 4 58 6 |
| 5 34 28 | 2368 23468 2348 | 1 9 7 |
+-------------+------------------+------------+
| 7 5 4 | 123 23 9 | 8 6 12 |
| 9 26 3 | 1268 268 1278 | 5 12 4 |
| 26 8 1 | 4 2356 235 | 7 23 9 |
+-------------+------------------+------------+
| 1248 9 6 | 128 248 1248 | 3 7 5 |
| 1248 124 7 | 12358 23458 6 | 9 1248 128 |
| 3 124 5 | 1289 7 1248 | 6 1248 128 |
+-------------+------------------+------------+ |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Jan 23, 2010 8:33 pm Post subject: |
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| Quote: | | I had to find the hidden pair 35 before the xy-wing, which took much longer time than finding the old reliable. Or have I missed something? |
If you see my post above, I also had to find the 35 hidden pair. However, I don't use the hidden pair terminology, I use the complementary subset which, in this case, was the quad of 1248. |
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Wendy W
Joined: 04 Feb 2008
Posts: 144
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| Posted: Sat Jan 23, 2010 9:33 pm Post subject: |
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| I agree with those of you who thought this one was a lot trickier than usual. But I did get to use a swordfish (took the 6 out from R3C5)! Good puzzle. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sun Jan 24, 2010 2:52 am Post subject: |
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| lpj004 wrote: | This puzzle didn't seem to be a VH. Only basic moves were needed.
At this stage, the "Grade" button showed "very hard", though clearly it isn't. Enter the 6 in r1c1 and grade shows "easy."
| Code: | +-------------+------------------+------------+
| 46 7 9 | 568 1 458 | 2 58 3 |
| 12 13 28 | 7 23589 2358 | 4 58 6 |
| 5 34 28 | 2368 23468 2348 | 1 9 7 |
+-------------+------------------+------------+
| 7 5 4 | 123 23 9 | 8 6 12 |
| 9 26 3 | 1268 268 1278 | 5 12 4 |
| 26 8 1 | 4 2356 235 | 7 23 9 |
+-------------+------------------+------------+
| 1248 9 6 | 128 248 1248 | 3 7 5 |
| 1248 124 7 | 12358 23458 6 | 9 1248 128 |
| 3 124 5 | 1289 7 1248 | 6 1248 128 |
+-------------+------------------+------------+ |
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I agree, from the position you posted, the puzzle is only singles. But, how did you get to this point?
In particular, how did you solve R7C3 as 6?
Delete the solved 6 in R7C3, and you have:
| Code: | +-------------------+-------------------+-------------------+
| 468 7 9 | 568 1 458 | 2 58 3 |
| 128 123 28 | 7 23589 2358 | 4 58 6 |
| 5 2346 268 | 2368 23468 2348 | 1 9 7 |
+-------------------+-------------------+-------------------+
| 7 5 4 | 123 23 9 | 8 6 12 |
| 9 26 3 | 1268 268 1278 | 5 12 4 |
| 26 8 1 | 4 2356 235 | 7 23 9 |
+-------------------+-------------------+-------------------+
| 12468 9 268 | 128 248 1248 | 3 7 5 |
| 1248 124 7 | 12358 23458 6 | 9 1248 128 |
| 3 124 5 | 1289 7 1248 | 6 1248 128 |
+-------------------+-------------------+-------------------+ |
Now, what?
Keith |
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Ema Nymton
Joined: 17 Apr 2009
Posts: 89
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| Posted: Sun Jan 24, 2010 9:36 am Post subject: |
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Please forgive my ignorance. I am having problems following your line of reasoning.
| Marty R. wrote: |
Ema, ... the 1248 quad in row 8.
... 35 in r8c5. . |
What does the 1248 quad mean?
How did you find the 'hidden' 35 in r8c5? At this point the possibilities are '23458'. Where did the '248' go?
It is obvious, the depth of the reasoning in the problem solving techniques has eluded me.
Ema
Seeking more answers.
~@:o?
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sun Jan 24, 2010 1:21 pm Post subject: |
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| Quote: | | How did you find the 'hidden' 35 in r8c5? At this point the possibilities are '23458'. Where did the '248' go? |
In the row, 3 and 5 only occur together, and they only occur in two cells. Those cells can only be 35. That is the hidden pair.
Or, by the same token, the candidates 1248 can be found in four cells that contain no other candidates. That is the quad.
Keith |
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Ema Nymton
Joined: 17 Apr 2009
Posts: 89
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| Posted: Sun Jan 24, 2010 2:28 pm Post subject: |
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| keith wrote: |
In the row, 3 and 5 only occur together, and they only occur in two cells. Those cells can only be 35. That is the hidden pair.
Or, by the same token, the candidates 1248 can be found in four cells that contain no other candidates. That is the quad.
Keith |
Now that you point it out to me, I can see the '35'. And more importantly _why_.
Humbly, I thank you.
Ema
~@:o)
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Tue Jan 26, 2010 5:09 am Post subject: |
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I uploaded a walkthrough here...
1-23-10-VH |
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strmckr
Joined: 18 Aug 2009
Posts: 64
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| Posted: Tue Jan 26, 2010 8:45 am Post subject: |
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| Code: | .------------------.--------------------.--------------.
| 468 7 9 | 568@ 1 -458 | 2 58 3 |
| 128 123 28 | 7 9 -2358 | 4 58 6 |
| 5 2346 268 | 2368 23468 2348 | 1 9 7 |
:------------------+--------------------+--------------:
| 7 5 4 | 123 23@ 9 | 8 6 12 |
| 9 26 3 | 1268 268 7 | 5 12 4 |
| 26 8 1 | 4 256 25@ | 7 3 9 |
:------------------+--------------------+--------------:
| 12468 9 268 | 128 248 1248 | 3 7 5 |
| 1248 124 7 | 12358@ 23458@ 6 | 9 1248 128 |
| 3 124 5 | 9 7 1248 | 6 1248 128 |
'------------------'--------------------'--------------' |
i found this at the start before i did anything.
AIC 5- r1c4 =5= r8c4 =3= r8c5 -3- r4c5 -2- r6c6 -5 => r12c6<>5
all singles to the end...... |
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