## unique solutions

Post the puzzle or solving technique that's causing you trouble and someone will help

### whoops

I meant the impossible 7 was in r7c7, the 7 in r7c1 is forced by r8c6
rds2301

Posts: 10
Joined: 20 December 2005

### Re: whoops

[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.

tarek

Posts: 2699
Joined: 05 January 2006

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

tarek

Posts: 2699
Joined: 05 January 2006

### simple guess

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

Posts: 10
Joined: 20 December 2005

### Re: simple guess

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).

tarek

tarek

Posts: 2699
Joined: 05 January 2006

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

Posts: 798
Joined: 22 June 2005

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