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Puzzle 10/04/07 (B)

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed Apr 07, 2010 5:03 pm    Post subject: Puzzle 10/04/07 (B) Reply with quote

Hard VH+ ?

Code:
 +-----------------------+
 | 1 . 6 | . . 4 | 9 5 . |
 | . 8 5 | . . 9 | . . 6 |
 | 9 4 . | 6 5 . | . 2 . |
 |-------+-------+-------|
 | . . 3 | 2 . . | . 6 . |
 | . . 4 | . 3 . | . . . |
 | 8 6 . | . . 5 | . . . |
 |-------+-------+-------|
 | 6 . . | . . . | . . 3 |
 | 4 . 8 | 5 . . | . . 2 |
 | . 3 . | . . . | 6 9 5 |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Wed Apr 07, 2010 6:02 pm    Post subject: Reply with quote

This was a doozie because I went looking at chains and then decided on a different tack altogether !

Quote:
1. UR in blocks 7 and 8 on <12> eliminating 1s in r79c6

2.A "skinny" finned swordfish on 1s in r269 eliminating 1s inR4C7 R5C8


Very Entertaining!!
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Wed Apr 07, 2010 10:18 pm    Post subject: Reply with quote

In my solution for this puzzle, there seems to be a critical combination of initial steps for it to qualify as VH+.
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Thu Apr 08, 2010 3:32 am    Post subject: Reply with quote

Fun puzzle!

Code:

 *-----------------------------------------------------------*
 | 1     2     6     | 3     78    4     | 9     5     78    |
 | 3     8     5     | 17    2     9     | 147   147   6     |
 | 9     4     7     | 6     5     18    | 3     2     18    |
 |-------------------+-------------------+-------------------|
 | 5     17    3     | 2     49    178   | 178   6     49    |
 | 2     17    4     | 1789  3     6     | 5     178   179   |
 | 8     6     9     | 147   147   5     | 2     3     147   |
 |-------------------+-------------------+-------------------|
 | 6     5     12    | 179   179   127   | 48    48    3     |
 | 4     9     8     | 5     6     3     | 17    17    2     |
 | 7     3     12    | 148   148   128   | 6     9     5     |
 *-----------------------------------------------------------*

Looking at the outside requirements for the UR12 in r79c36, we find:
digit 1: in r34c6
digit 2: x-wing overlay
Thus a 1 must exist in r3c6 or r4c6 to prevent the deadly pattern.
This strong link can be used to form a flightless w-wing 17 with pincers on 7 in r2c4 and r4c2.
Transport the 7 pincer in r2c4: (7)r2c4 - r1c5 = r1c9 - r56c9 => in b6, either r4c7=7 or r5c8=7
(7)r4c7; r4c6<>7,
(7)r5c8 - r5c2 = r4c2; r4c6<>7 thereby deleting 7 in r4c6.

AIC: (1=9)r7c5 - (9=4)r4c5 - (4=8)r9c5 - (8=7)r1c5 - (7=1)r2c4; r7c4<>1

To complete, a finned xy-wing -178 with vertex 78 in r5c4, pincer 17 in r2c4, pincer 18 in r4c6 and fin 1 in r5c4.
If xy-wing is true, then r6c4<>1 and r3c6<>1,
If fin is true. then only r6c4<>1.
Thus r6c4<>1 to complete the puzzle.

Ted
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Thu Apr 08, 2010 5:10 am    Post subject: Reply with quote

This was a fun BBDB for me. I used nine assorted steps including URs, XY, XYZ, Fin Transport, Coloring, W-Wing with pincer transport and ending on an M-Wing.
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Thu Apr 08, 2010 2:32 pm    Post subject: Reply with quote

Mogulmeister wrote:
This was a doozie because I went looking at chains and then decided on a different tack altogether !

Quote:
1. UR in blocks 7 and 8 on <12> eliminating 1s in r79c6

2.A "skinny" finned swordfish on 1s in r269 eliminating 1s inR4C7 R5C8


Very Entertaining!!


I assume you mean columns 269?

This one cropped up for me but I was looking at it from a multi-colouring perspective with clusters in c2, c6 and then a grouped colouring in c9 with r56c9 being my group.

I rarely ever "see" Swordfish - never mind finned ones! Good spot!
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Thu Apr 08, 2010 3:47 pm    Post subject: Reply with quote

Thanks Peter - that is indeed what I meant!

I always look for swordfish after X-wings - same principal just one more row.

For some reason, I always get pleased when I find a jellyfish as well.

One of the other current daj puzzles (10/04/07 (A)) has a very nice jellyfish at the start. In fact when you start you can see an X-wing and there's a swordfish and a jellyfish - all on 9s! Bit like those crazy Xmas roasts where a turkey contains a duck contains a chicken.

I know its not to do with THIS puzzle but here it is anyway - eliminateds in blue. Notice the X-wing in pink and can you see the swordfish as well ?

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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Thu Apr 08, 2010 4:53 pm    Post subject: Reply with quote

Thanks. Yes can see it - though the different colours do a good job of hiding it!
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Thu Apr 08, 2010 5:19 pm    Post subject: Reply with quote

Rolf Harris ??
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