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hollydoll
Joined: 04 Nov 2005 Posts: 1 Location: Vermont

Posted: Sun Dec 04, 2005 1:08 pm Post subject: Help! 


I have gotten this far and am stuck. I have tried all I know. Perhaps I overlooked something  I guess I did! Thanks.
Code:  6x3 x28 7x5
5xx 3xx x18
8x4 xxx xx3
3xx x16 579
xxx x3x x86
x65 87x 3x1
xxx x5x 962
756 982 134
xx9 64x 857 
________
herb scales
Last edited by hollydoll on Thu Feb 03, 2011 8:41 pm; edited 1 time in total 

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someone_somewhere
Joined: 07 Aug 2005 Posts: 275 Location: Munich

Posted: Sun Dec 04, 2005 2:04 pm Post subject: 


Hi,
This requires a couple of advanced techniques (hidden triple, XYWing), at this moment:
Code:  9 not in r5c2, it is in r5c1 or r6c1 (Column on 3x3 Block interaction)
9 not in r2c6, it is in r2c5 or r3c5 (Column on 3x3 Block interaction)
9 not in r3c6, it is in r2c5 or r3c5 (Column on 3x3 Block interaction)
1 not in r5c2, it is in r1c2 or r3c2 of the 3x3 (3x3 Block on Row/Column interaction)
1 not in r7c2, it is in r1c2 or r3c2 of the 3x3 (3x3 Block on Row/Column interaction)
1 not in r9c2, it is in r1c2 or r3c2 of the 3x3 (3x3 Block on Row/Column interaction)
2 not in r3c2, Hidden Triple 1 5 7 in r3c2 r3c4 r3c6
9 not in r3c2, Hidden Triple 1 5 7 in r3c2 r3c4 r3c6
2 not in r2c7, it is in r3c7 or r3c8 (Row on 3x3 Block interaction)
2 not in r5c1, XYWing X=8 Y=1 in r7c3 X=8 Z=2 in r4c3 Y=1 Z=2 in r9c1
2 not in r6c1, XYWing X=8 Y=1 in r7c3 X=8 Z=2 in r4c3 Y=1 Z=2 in r9c1
7 not in r7c6, XYWing X=1 Y=4 in r1c4 X=1 Z=7 in r7c4 Y=4 Z=7 in r2c6
2 in r6c8 7 in r7c4  Unique Horizontal 
hope this helps.
see u, 

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David Bryant
Joined: 29 Jul 2005 Posts: 559 Location: Denver, Colorado

Posted: Sun Dec 04, 2005 4:11 pm Post subject: Here's another way to crack it 


That's an interesting solution, someone. Here's another way to crack this nut.
I used "coloring," which uncovered a hidden pair in column 2, and that cracked it. The short answer is that r9c2 = 3. The rest of it is pretty easy to solve, once you get that one. Let me explain.
Here's the grid, with all the possibilities shown. It should be fairly obvious how we get to this.
Code:  6 19 3 14 2 8 7 49 5
5 279 27 3 69 47 46 1 8
8 17 4 157 69 157 26 29 3
3 248 28 24 1 6 5 7 9
1249 2479 127 245 3 459 24 8 6
249 6 5 8 7 49 3 24 1
14 348 18 17 5 137 9 6 2
7 5 6 9 8 2 1 3 4
12 23 9 6 4 13 8 5 7 
The critical value is "4". We're going to use a "coloring" argument to show that the {4, 8} pair lies in r4c2 & r7c2. To do that we must eliminate the possibility of a "4" at r5c2.
Note first that there are only two ways a "4" can fit in row 4  it's either at r4c2 or else it's at r4c4.
Now look at the top center 3x3 box. There are only two ways a "4" can fit in there  either at r1c4 or at r2c6. There are also only two ways to fit a "4" in row 2  at r2c6 or at r2c7. And there are only two ways to fit a "4" in column 7  at r2c7 or at r5c7. Following this chain we can see that there's either a "4" at r1c4, or else there's a "4" at r5c7.
Now we put the two chains together:
r4c2 = 4 ==> r5c1 <> 4 and r5c2 <> 4
r4c2 <> 4 ==> r4c4 = 4 ==> r1c4 <> 4 ==> r5c7 = 4 ==> r5c1 <> 4 and r5c2 <> 4
So we can eliminate the possibility of a "4" at r5c1 and at r5c2  now we can see the hidden pair in column 2, plus the quadruplet {1, 2, 7, 9} in r1c2, r2c2, r3c2, & r5c2, and the "3" in column 2 has to go at r9c2. dcb 

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