Can this be solved without guessing?

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Can this be solved without guessing?

Postby tonyburnaby » Thu Oct 25, 2012 7:38 am

I am stuck, could be done by guessing and trial/error, but I am wondering whether I can solve this puzzle just by logical thinking without guessing? thanks a lot.

Here is the puzzle:

Image
tonyburnaby
 
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Joined: 25 October 2012

Re: Can this be solved without guessing?

Postby JC Van Hay » Thu Oct 25, 2012 10:31 am

Analysis of the puzzle :

    Implications of the 8 cells containing the digits 57 (using Red Green Transport)!

    If r1c4=5 => r4c2=5, r8c2=9, r1c2=8=r6c1, r5c1=1
    While
    If r1c4=7 => r8c1=9; r5c1=1

    Furthermore, r5c1=1 => r1c4=7

    Finally : r6c1=1 => r5c1=9 & r1c1=8, r1c2=9; no 9 in R8!
Interpretation :

    #1. Chain[4] : 8r6c1=8r1c1-(8=9)r1c2-9r8c2=9r8c1-(9=1)r5c1 :=> -1r6c1; 16 singles
======================================================================

The puzzle is then solved using :

    #2. BUG+1 : +5r6c2; singles to the end
    Or
    #2. Chain[3] : XY Wing : (8=5)r6c1-(5=98)r14c2 :=> -8r1c1.r6c2; singles to the end
JC Van Hay
 
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Re: Can this be solved without guessing?

Postby tonyburnaby » Sat Oct 27, 2012 1:41 am

a bit overwhelming, but I finally got your explanation, thanks so much!
tonyburnaby
 
Posts: 3
Joined: 25 October 2012


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