Next step for solving this puzzle

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Next step for solving this puzzle

Postby sebyastiens » Tue Mar 17, 2020 4:05 pm

Hello,

I solved both of these with trials & errors at that stage (see screenshot) but I was wondering if there is a technique I could have used before using trial & error process.

I only know X wing, swordfish, unique rectangle and XY wing which I didn't find the possibility to apply at that stage.

Thanks for your help
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Re: Next step for solving this puzzle

Postby dxSudoku » Tue Apr 07, 2020 1:51 am

Here are the two hard steps:
Hidden Rectangle: 3/5 in r4c69,r6c69 => r6c9<>5
XY-Chain: 7 7- r1c6 -6- r1c3 -4- r8c3 -5- r9c2 -4- r9c9 -7 => r1c9<>7

After these it's bunch of Naked and Hidden Singles.
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Re: Next step for solving this puzzle

Postby Wepwawet » Fri Apr 10, 2020 6:19 pm

Well, you can start by eliminating the 6 from r4c9, and if you are familiar with Unique Rectangles, then you will be aware of Hidden Rectangles: 3/5 in r4c69 and r6c69 leading to the elimination of 5 from r6c9.

An XY Chain and a W-Wing would see you home and dry, but I don't know if you are familiar with these.
Alternatively, by contradiction the 3 at r6c9 can be eliminated, as it leads to there being two 4's in row 5, and without the 3 in r6c9, it is plain sailing all the way home.
Hope that helps!
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