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sat 5th very hard

 
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George Woods



Joined: 28 Mar 2006
Posts: 238
Location: Dorset UK

PostPosted: Sun Aug 06, 2006 5:27 pm    Post subject: sat 5th very hard Reply with quote

Always looking for the more direct route I wonder is there a better one?

After some fairly mundane entries I reached r7c5 which might be 1 5 or 8

An X wing in r48c35 denies a 1 in this position

The 5 is denied by a bit of reasoning that may not have a formal description.

To leave a position for 5 in col 1 there must be a 5 in either c5 row 2 or 8
So a 5 in col 5 at either r3 or 7 denies this

Hence r7c5 is 8 and so on to a solution.

So what is the better solution?


the crunch point to which above refers is

018 020 075
702 106 049
009 000 100

920 005 006
040 060 250
800 200 091

070 000 900
290 304 007
080 090 510
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David Bryant



Joined: 29 Jul 2005
Posts: 559
Location: Denver, Colorado

PostPosted: Sun Aug 06, 2006 6:54 pm    Post subject: X-Wing on "5" Reply with quote

George --

There's another X-Wing -- on "5"s -- in columns 1 & 4 (and in rows 3 & 7, specifically), which eliminates the "5" at r7c5. dcb
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Blas



Joined: 19 Jul 2005
Posts: 8

PostPosted: Mon Aug 07, 2006 6:41 am    Post subject: Sat 5th Aug puzzle continued Reply with quote

Being very dim, I cannot get the 5 in r1c9, which George Woods found. George - how did you get it, please?
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TKiel



Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI

PostPosted: Mon Aug 07, 2006 12:28 pm    Post subject: Reply with quote

Blas,

After playing the 5 singles at the start of the puzzle, that leaves a naked pair in box 6. After making those exclusions from the rest of that box, the only 3's remaining in column 7 lie in box 3, which means all other 3's in that box can be excluded. This leaves r1c9 with only 5 as a candidate.
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Blas



Joined: 19 Jul 2005
Posts: 8

PostPosted: Mon Aug 07, 2006 5:18 pm    Post subject: Sat puzzle Reply with quote

I can NOT believe it; I really must get my eyes tested; what a prat I am. Many thanks, Tracy.
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