## X-chain question

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

### X-chain question

Why is box 9 a weak link in this chain?
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Houdini

Posts: 3
Joined: 15 October 2019

### Re: X-chain question

Welcome, Houdini.

It is a strong link, which here works as a weak link.

The logic is:
If 8 "is not" in r5c8, it "must be" in r8c8 (strong link),
if it "is" in r8c8, it "can't be" in r7c7 (weak link, also correct with a strong link),
if it "is not" in r7c7, ...
(you can do that from the other side as well)

At the end you know, that if 8 is not in r5c8, it must be in r6c6, i.e. either 8 is in r5c8 or in r6c6 or in both of them.
eleven

Posts: 2461
Joined: 10 February 2008

### Re: X-chain question

Thanks eleven. I didn't realize a strong link could take the place of a weak like that in an x-chain. I see that following the logic around makes sense. I will have to change the way I search for these chains.
Houdini

Posts: 3
Joined: 15 October 2019