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Extreme - finned squirmbag to the rescue ?

 
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Mogulmeister



Joined: 03 May 2007
Posts: 695

PostPosted: Thu May 03, 2007 11:17 am    Post subject: Extreme - finned squirmbag to the rescue ? Reply with quote

I thought on the return of this board that I'd like to share this puzzle I've been chewing over. It is the current Extreme #32 and is from the Mepham site so it's one of Andrew Stuart's. You won't be able to run his solver on it until Sunday ! Smile

Here it is in its original form:


Code:

+---+---+---+
|...|...|...|
|.1.|.5.|89.|
|9..|1.2|...|
+---+---+---+
|.5.|3.9|.17|
|..9|.6.|5..|
|86.|7.5|.3.|
+---+---+---+
|...|5.6|..8|
|.34|.1.|.6.|
|...|...|...|
+---+---+---+


Last edited by Mogulmeister on Thu May 03, 2007 12:11 pm; edited 1 time in total
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Mogulmeister



Joined: 03 May 2007
Posts: 695

PostPosted: Thu May 03, 2007 11:27 am    Post subject: To continue Reply with quote

I arrived at this point and noticed what (I think??) is a "finned squirmbag"
however, better minds than mine can probably advise.......

This is on 2's. The squirmbag is in green, the "fin" is salmon pink and the eliminated 2's in blue. The puzzle solves easily thereafter.



I'd be interested in:

a)Comments - is this so ?
b)What other solving paths would you follow ?

Thanks. Mogul
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Ruud



Joined: 18 Jan 2006
Posts: 31

PostPosted: Thu May 03, 2007 7:20 pm    Post subject: Reply with quote

You have correctly identified a finned squirmbag, but it does not yield any eliminations.

EITHER the candidate 2 in R2C1 is true OR the squirmbag for digit 2 in columns 12578 is true. You would only be allowed to eliminate digit 2 from R3C12 if they were present.

Alternative steps:

Finned X-Wing for digit 4 in rows 25, columns 49 with fin in R2C6, eliminates digit 4 in R1C4.

Finned Swordfish for digit 2 in rows 258, columns 149 with fin in R8C7, eliminates digit 2 in R9C9.

ALS-XY rule: A=R1C2 {2,4}, B= R2C1346 {23467}, X (restricted common) = 2 (in box 1), Z=4. Digit 4 can be eliminated from R1C56.

After that, the puzzle still requires several advanced steps like Nishio (digit 2), 3D coloring, Swordfish, XY-Chain.

Ruud
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Mogulmeister



Joined: 03 May 2007
Posts: 695

PostPosted: Thu May 03, 2007 7:41 pm    Post subject: Reply with quote

Sorry Ruud you refer to R3C12 but that is just a 9 and 48 - I don't see any 2 present. Please enlighten - I'm being a bit slow today.
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Ruud



Joined: 18 Jan 2006
Posts: 31

PostPosted: Thu May 03, 2007 7:57 pm    Post subject: Reply with quote

Ruud wrote:
...if they were present...
they are not.

A finned squirmbag in columns 12578, rows 16789 with a fin in R2C1 would eliminate all candidates in columns 1&2 which can "see" the fin in R2C1. R3C12 are the only cells which fit this description, but there are no candidates for digit 2 in those cells.

You got the pattern right, but the eliminations wrong. The only candidates it could eliminate are already gone.

Ruud
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Mogulmeister



Joined: 03 May 2007
Posts: 695

PostPosted: Thu May 03, 2007 8:55 pm    Post subject: Reply with quote

Thanks Ruud. So in effect the blue eliminations only apply when the Squirmbag is true and the fin is false. I certainly wouldn't want to truth table that lot.
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Mogulmeister



Joined: 03 May 2007
Posts: 695

PostPosted: Thu May 17, 2007 7:46 am    Post subject: Reply with quote

Interestingly, the squirmbag is true in this case which is why the eliminations worked.
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