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ZeroAssoluto
Joined: 05 Feb 2017 Posts: 941 Location: Rimini, Italy
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Posted: Fri Oct 29, 2021 8:52 am Post subject: Oct 29 VH |
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Hi everyone,
Code: |
+----------+--------+-------------+
| 16 8 7 | 4 9 36 | 2 13 5 |
| 156 9 56 | 2 8 37 | 37 4 16 |
| 2 3 4 | 5 1 67 | 678 9 68 |
+----------+--------+-------------+
| 8 4 39 | 6 7 1 | 5 23 29 |
| 7 2 39 | 8 4 5 | 13 6 19 |
| 56 1 56 | 3 2 9 | 4 8 7 |
+----------+--------+-------------+
| 9 6 18 | 7 3 2 | 18 5 4 |
| 3 7 18 | 9 5 4 | 168 12 1268 |
| 4 5 2 | 1 6 8 | 9 7 3 |
+----------+--------+-------------+
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Play this puzzle online at the Daily Sudoku site
Quote: | XY-Wing 1,2,3 in r48c8,r5c7 and -1 in r78c7
or
UR 5,6 in r26c13 and r2c1=1 |
Ciao Gianni |
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TomC
Joined: 30 Oct 2020 Posts: 358 Location: Wales
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Posted: Fri Oct 29, 2021 1:50 pm Post subject: |
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Pincers on 1's in r1c8 and r5c9 give -1 in r2c9 so r2c9=6 |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Fri Oct 29, 2021 2:52 pm Post subject: |
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R2C1 must be 1 because of the UR* at r26c13.
*Unique Rectangle.
Last edited by Mogulmeister on Fri Oct 29, 2021 3:09 pm; edited 1 time in total |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Fri Oct 29, 2021 3:08 pm Post subject: |
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TomC wrote: | Pincers on 1's in r1c8 and r5c9 give -1 in r2c9 so r2c9=6 |
Looks like a long backed chair ! |
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TomC
Joined: 30 Oct 2020 Posts: 358 Location: Wales
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Posted: Fri Oct 29, 2021 3:22 pm Post subject: |
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I saw it as a dog leg! (your chair would fall over)
Just noticed with the pincers, you could have r8c8=2 as otherwise it would force r2c9=1 |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Fri Oct 29, 2021 3:27 pm Post subject: |
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TomC wrote: | I saw it as a dog leg! (your chair would fall over) |
Right enough but I incorporated the single 6 to hold it up. Like those dodgy constellations in the night sky. |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Sat Oct 30, 2021 12:18 am Post subject: |
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Mogulmeister wrote: | R2C1 must be 1 because of the UR* at r26c13.
*Unique Rectangle. |
OK already posted by Gianni. I couldn't do the right click reveal on my iphone while I was out - sorry for repeating.
So instead look at r5c9.
If it is 1 then obviously r5c7 two doors down, is going to = 3
But lets follow that 1 again but take a different chain route
(9=1)r5c9-r2c9=(1-3)r1c8=(3-7)r2c7-(3=1)r5c7 so r5c7 < > 3
So a contradiction when you put a 1 in r5c9 it can also put a 1 (not 3) in r5c7.
Clearly r5c9 < > 1 |
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TomC
Joined: 30 Oct 2020 Posts: 358 Location: Wales
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Posted: Sat Oct 30, 2021 10:17 am Post subject: |
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Nice contradiction
Another way to view this is to focus on r1c8 <13>
If either r5c7=3 or r5c9=1 you would get r1c8 containing both 1 and 3 |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Mon Nov 01, 2021 10:26 am Post subject: |
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Nice obverse!
Contradiction Recapitulation
We can see that the contradiction world can:
1)Put too many of the same numbers into a house
2)Remove a number totally from a house
3)Create a loop where the starting number is removed
4)Create a loop where a number is forced in even when removed at the start
5)Create multiple numbers in the same square location as the answer
6)Remove all numbers so the a square is vacant |
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