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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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 Posted: Fri Apr 11, 2008 4:30 am Post subject: competition #1006 |
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| Code: | . . 2 | 4 . 7 | 5 . .
. 6 3 | . . 1 | 8 . .
. . . | . . . | . . 9
- - - + - - - + - - -
3 . . | 6 . . | . . .
7 . . | 2 . 3 | . . 6
. . . | . 1 8 | . . 7
- - - + - - - + - - -
2 . . | . . . | . . .
. . 7 | 3 . . | 1 9 .
. . 8 | 7 . 6 | 2 . . |
I used coloring and an xy-chain
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a bonus puzzle from sudokupuzz
| Code: | . 5 8 | . 4 . | 1 6 .
4 . . | . . . | . . 8
. . 3 | . . . | 9 . .
- - - + - - - + - - -
. 4 . | 3 . 9 | . . .
3 . . | . . . | . . 5
. . . | 4 . 1 | . 8 .
- - - + - - - + - - -
. . 4 | . . . | 7 . .
2 . . | . . . | . . 6
. 9 5 | . 7 . | 8 1 . |
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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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| Posted: Fri Apr 11, 2008 7:20 am Post subject: |
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You missed a W-wing in the first one - we can all do it. Very peaceful puzzle!
Working on the 2nd, which doesn't seem straightforward. |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Fri Apr 11, 2008 7:31 am Post subject: |
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Second puzzle: After x-wing
| Code: | *------------------------------------------------------------*
| 79 5 8 | 79 4 23 | 1 6 23 |
| 4 1267 -12679 | 15679 12369 2567 | 25 2357 8 |
|#17 1267 3 | 15678 1268 25678 | 9 2457 @247 |
|-------------------+----------------------+-----------------|
| 58 4 @267 | 3 58 9 | 26 @27 1 |
| 3 1268 1269 | 678 268 2678 | 246 249 5 |
| 579 267 2679 | 4 256 1 | 3 8 @279 |
|-------------------+----------------------+-----------------|
|-18 138 4 | 15689 13689 568 | 7 2359 29 |
| 2 1378 #17 | 1589 1389 458 | 45 3459 6 |
| 6 9 5 | 2 7 34 | 8 1 34 |
*------------------------------------------------------------* |
w-wing 17 connected with a kite for 7. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Fri Apr 11, 2008 4:20 pm Post subject: |
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in the competition puzzle,
there is a w-wing on {4,5} and {2,5}
the 4,5 doesn't solve it tho. |
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Steve R
Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England
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| Posted: Fri Apr 11, 2008 4:53 pm Post subject: |
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Excellent spot, ravel!
The X-wing is not actually needed, so you have reduced it to a one-trick puzzle. Chapeau!
Steve |
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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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| Posted: Fri Apr 11, 2008 6:06 pm Post subject: |
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Sorry if I got it wrong S_N. I've thrown away my sheet and can't check without doing it again. (I just know that I often miss W-wings & someone comes along later & makes it seem easy.)
Smart stuff Ravel - chapeau off indeed! |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Fri Apr 11, 2008 6:35 pm Post subject: |
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| Victor wrote: | Sorry if I got it wrong S_N. I've thrown away my sheet and can't check without doing it again. (I just know that I often miss W-wings & someone comes along later & makes it seem easy.)
Smart stuff Ravel - chapeau off indeed! |
I didn't see the w-wings the first time through. but now that I studied it more, I see two. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Fri Apr 11, 2008 6:56 pm Post subject: |
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| ravel wrote: | Second puzzle: After x-wing
| Code: | *------------------------------------------------------------*
| 79 5 8 | 79 4 23 | 1 6 23 |
| 4 1267 -12679 | 15679 12369 2567 | 25 2357 8 |
|#17 1267 3 | 15678 1268 25678 | 9 2457 @247 |
|-------------------+----------------------+-----------------|
| 58 4 @267 | 3 58 9 | 26 @27 1 |
| 3 1268 1269 | 678 268 2678 | 246 249 5 |
| 579 267 2679 | 4 256 1 | 3 8 @279 |
|-------------------+----------------------+-----------------|
|-18 138 4 | 15689 13689 568 | 7 2359 29 |
| 2 1378 #17 | 1589 1389 458 | 45 3459 6 |
| 6 9 5 | 2 7 34 | 8 1 34 |
*------------------------------------------------------------* |
w-wing 17 connected with a kite for 7. |
ok, my learning curve on these w-wings ( cycles ) is starting to jump seven fold. especially after studying this kite example.
that kite, if you color the sevens in Ravel's grid, start with red on the 7 in r3c1, that means the 7 in r8c3 is green. that means that those sevens would create a pincer and eliminate any sevens they see, but you can extend it in this case because they share a 1 in both cells and therefore either r3c1 has to be a one or r8c3 has to be a one and the 1 in r7c1 is gone.
sweet !!!
so now my question is, do the pincer cells have to contain just two candidates for this to work?? or can there be an elimination like a UR type 3 where a naked pair is formed?? if more than two candidates are in the pincer cells?
for example, lets the say the pincer cells contained {1,2,7} instead of {1,7}
would that act like a naked pair?? |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Fri Apr 11, 2008 11:34 pm Post subject: |
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No, it would not say more than "one of them cant be 7".
I saw this from the other side. There is the remote pair 17, are there strong links for 1 or 7, that connect the cells ? The one for 7 in column 9 only sees r3c1, but 7 in r6c9 could be "transported" to r4c3, which sees the other pair.
If i start with the "useless" kite for 7, i could see following (if i ignore the 17's now):
r3c9=7 or r4c3=7
r4c3=7 only implies r4c7=6 directly
r3c9=7 implies r9c9=4 and then many numbers including r7c7=5, r2c7=2, r4c7=6
so r4c7 must be 6
(this does not help much) |
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