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ravel
Joined: 21 Apr 2006
Posts: 536
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 Posted: Tue Jan 15, 2008 2:32 pm Post subject: Harder |
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| Code: | +-------------------+
| . 1 . . . . . . . |
| . . 3 . . . . . . |
| . 2 . 4 . . 9 1 . |
| . . . 7 . 2 . . 5 |
| . 3 . 1 . 6 . . . |
| . . 1 . . . 2 7 . |
| 9 4 . . . . . . 8 |
| . . . . . 7 . . 6 |
| . . . . . . 4 2 . |
+-------------------+
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... but nice to solve anyway. |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Wed Jan 16, 2008 8:04 pm Post subject: |
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Harder. Very true. This one is for the long winter night.
Nice going, brick wall.
Some xy chains, a bit of coloring... more chain.
Finally (!) done.
But I was expecting one or two URs for sure, coming from you, ravel. Maybe I just didn't look hard enough  |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Jan 17, 2008 12:53 am Post subject: |
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| does it say "DS" ?? |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Jan 17, 2008 1:15 am Post subject: |
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| Code: | 4678 1 49 | 25689 27 589 | 356 358 24
4678 6-89 3 | 25689 127 1589 | 56 *58 24
568 2 58 | 4 68 3 | 9 1 7
---------------------------------------------------------------------
48 89 49 | 7 3 2 | 1 6 5
2 3 7 | 1 5 6 | 8 4 9
56 56 1 | 89 89 4 | 2 7 3
---------------------------------------------------------------------
9 4 256 | 2356 12 15 | 7 *35 8
1 *58 258 | 2358 4 7 |*35 9 6
3 7 568 | 5689 689 589 | 4 2 1
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xy-chain ( mentioned by nataraj ) 58-35-35-58 removes 8 in r2c2 |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Jan 17, 2008 1:31 am Post subject: |
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I see some DP patterns that I can't prove, of course, lol.
in r12c159 the {2,4} {2,7} {4,7} pairs
in r69c45 the {8,9} pairs
norm |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Thu Jan 17, 2008 9:18 am Post subject: |
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| storm_norm wrote: | | does it say "DS" ?? |
Yes, as an homage to this site i generated some thousands of puzzles with this pattern. i hope, i can drop an interesting one here from time to time. | Quote: | | in r12c159 the {2,4} {2,7} {4,7} pairs |
Yes, this was the start for my solution. To destroy the DP one of the three numbers must be outside it in rows 1 and 2, i.e. r1c3=4 or r12c4=2
| Code: | *-----------------------------------------------------*
|#4678 1 *49 |*25689 #27 589 | 356 358 #24 |
|#4678 689 3 |*25689 #127 1589 | 56 58 #24 |
| 568 2 58 | 4 68 3 | 9 1 7 |
|-----------------+-------------------+---------------|
|*48 89 49 | 7 3 2 | 1 6 5 |
| 2 3 7 | 1 5 6 | 8 4 9 |
| 56 56 1 | 89 89 4 | 2 7 3 |
|-----------------+-------------------+---------------|
| 9 4 256 | 2356 1*2 15 | 7 35 8 |
| 1 58 258 | 2358 4 7 | 35 9 6 |
| 3 7 568 | 5689 689 589 | 4 2 1 |
*-----------------------------------------------------* |
r12c4=2 => r78c4<>2 => r7c5=2
r1c3=4 => r1c9=2
Eliminates 2 from r1c5
(Alternatively you can deduce it from r4c1=4 or r7c5=2)
| Code: | *---------------------------------------------------*
| 468 1 49 | 5689 7 589 | 356 358 2 |
| 7 @689 3 | 25689 12 1589 |#56 58 4 |
| 568 2 58 | 4 68 3 | 9 1 7 |
|----------------+-------------------+--------------|
| 48 89 49 | 7 3 2 | 1 6 5 |
| 2 3 7 | 1 5 6 | 8 4 9 |
| 56 #56 1 | 89 89 4 | 2 7 3 |
|----------------+-------------------+--------------|
| 9 4 256 | 2356 12 15 | 7 35 8 |
| 1 @58 258 | 2358 4 7 | 3-5 9 6 |
| 3 7 568 | 5689 689 589 | 4 2 1 |
*---------------------------------------------------* |
The w-wing 58 does not help much (r2c2<>8), but the "semi-M-wing" 56 connected by
r2c7=6 => r2c2<>6 => r6c2=6
together with the strong link for 5 in c2 means that one of r2c7 and r8c2 must be 5.
A skysrcaper later:
| Code: | *-----------------------------------------*
| 46 1 49 | 589 7 589 | 56 3 2 |
| 7 69 3 | 2 1 59 | 56 8 4 |
| 58 2 58 | 4 6 3 | 9 1 7 |
|-------------+---------------+-----------|
| 48 89 49 | 7 3 2 | 1 6 5 |
| 2 3 7 | 1 5 6 | 8 4 9 |
| 56 56 1 | 89 89 4 | 2 7 3 |
|-------------+---------------+-----------|
| 9 4 6 | 3 2 1 | 7 5 8 |
| 1 58 2 | 58 4 7 | 3 9 6 |
| 3 7 58 | 6 89 589 | 4 2 1 |
*-----------------------------------------* |
Another 6-cell DP solves it. |
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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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| Posted: Thu Jan 17, 2008 11:50 am Post subject: |
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The potential [89] DP* in R69C45 results in two pincer cells for digit <2> in R8C3(a) and R7C5(b), placing <2> in R8C3, because R9C4=5 or 6, or R9C5=6, or
both(R9C4=5 and R9C5=6). When R9C45=6 => [58] pair in C3 => R8C3=2 and when R9C4=5 => R7C5=2. Then i found a contradiction in C7 when R8C7=5 => R8C2=8 =>
R4C2=9 => R2C2=6 => R2C7=5 => R8C7≠5
| Code: |
+--------------------------+--------------------------+--------------------------+
| 4678 1 49 | 25689 27 589 | 356 358 24 |
| 4678 689 3 | 25689 127 1589 | 56 58 24 |
| 568 2 58 | 4 68 3 | 9 1 7 |
+--------------------------+--------------------------+--------------------------+
| 48 89 49 | 7 3 2 | 1 6 5 |
| 2 3 7 | 1 5 6 | 8 4 9 |
| 56 56 1 |*89 *89 4 | 2 7 3 |
+--------------------------+--------------------------+--------------------------+
| 9 4 -[2]56 | 2356 12(a) 15 | 7 35 8 |
| 1 58 (b)258 |-[2]358 4 7 | 35 9 6 |
| 3 7 568 |*5689 *689 589 | 4 2 1 |
+--------------------------+--------------------------+--------------------------+ |
After these two steps there is a Skyscraper@ for digit <8>, that takes out <8> in R1C1 and R3C5
| Code: |
+--------------------------+--------------------------+--------------------------+
| 4-[8]6 1 49 | 5689 7 @589 | 56 3 2 |
| 7 69 3 | 2 1 59 | 56 8 4 |
| 568 2 @58 | 4 6-[8] 3 | 9 1 7 |
+--------------------------+--------------------------+--------------------------+
| 48 89 49 | 7 3 2 | 1 6 5 |
| 2 3 7 | 1 5 6 | 8 4 9 |
| 56 56 1 | 89 89 4 | 2 7 3 |
+--------------------------+--------------------------+--------------------------+
| 9 4 6 | 3 2 1 | 7 5 8 |
| 1 58 2 | 58 4 7 | 3 9 6 |
| 3 7 @58 | 5689 689 @589 | 4 2 1 |
+--------------------------+--------------------------+--------------------------+ |
The final step is a 5-cell xy-chain with pincer ends at R8C4 and R2C6, eliminating both <5>'s in R9C6 and R1C4
| Code: |
+--------------------------+--------------------------+--------------------------+
| 46 1 49 |-[5]89 7 589 | 56 3 2 |
| 7 D 69 3 | 2 1 E 59 | 56 8 4 |
| 58 2 58 | 4 6 3 | 9 1 7 |
+--------------------------+--------------------------+--------------------------+
| 48 89 49 | 7 3 2 | 1 6 5 |
| 2 3 7 | 1 5 6 | 8 4 9 |
| 56 C 56 1 | 89 89 4 | 2 7 3 |
+--------------------------+--------------------------+--------------------------+
| 9 4 6 | 3 2 1 | 7 5 8 |
| 1 B 58 2 | 58 A 4 7 | 3 9 6 |
| 3 7 58 | 6 89 -[5]89 | 4 2 1 |
+--------------------------+--------------------------+--------------------------+ |
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