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whoops

Postby rds2301 » Sat Jan 21, 2006 2:23 am

I meant the impossible 7 was in r7c7, the 7 in r7c1 is forced by r8c6
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Re: whoops

Postby tarek » Sat Jan 21, 2006 2:32 am

[Deleted - as this post doesn't serve any purpose now]
Last edited by tarek on Sat Jan 21, 2006 6:53 am, edited 1 time in total.
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Postby tarek » Sat Jan 21, 2006 2:41 am

modifying the grid posted by tso, here is how the solver reached the conflict
Code: Select all
-----------------------------------------------------------------*
| .      7      .     | 7  .   7  .  -7 .   | .      .      .     |
| .      .      .     | .      .      .     | .     +7      .     |
| .      7      .     | 7  .   .     -7     | .      .      .     |
|---------------------+---------------------+---------------------|
| .      .      .     | .      .     -7     | .      .     -7     |
| .      .     +7     | .      .      .     | .      .      .     |
| .      .      .     | -7  .   -7    .     |+7      .      .     |
|---------------------+---------------------+---------------------|
|+7      .      .     | .      .      .     |-7  .   .     -7     |
|-7      .      .     |-7  .  -7    +[7]    | .      .     -7     |
| .      .      .     |-7     -7      .     | .      .     +7     |
*-----------------------------------------------------------------*

Note that all 7s in box 5 are excluded & hence the conflict
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simple guess

Postby rds2301 » Sat Jan 21, 2006 2:44 am

tried the 1 in r9c8 simple guess leads to contradiction, what is contradictory about r1c2, r2c2 and r7c1 and r8c1 all having a 1
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Re: simple guess

Postby tarek » Sat Jan 21, 2006 2:56 am

rds2301 wrote:tried the 1 in r9c8 simple guess leads to contradiction, what is contradictory about r1c2, r2c2 and r7c1 and r8c1 all having a 1


Simple guess would imply that if r9c8 would be 1, then single (naked/hidden) eliminations from there would lead eventually to a conflict (it doesn't have to be in 1s).

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Postby tso » Sat Jan 21, 2006 6:01 am

Tarek was correct -- all four Nishios are valid. Sorry for the confusion caused by my inaccurate post.
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