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PostPosted: Wed May 14, 2008 5:26 pm 
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According to this article, the Ostrich is the largest species of bird in this planet. It also has the longest legs and lays the biggest eggs. And it has the famous/hilarious behaviour of sticking its head into the sand when there is danger. I wonder if JC knew all these facts when he chose it to represent the (1,5) leaper in his JSudoku solver program. :)

So here is a 6x6 Sudoku variant puzzle as a tribute to this fascinating animal. The main rules are Ostrich-Non-Consecutive and Anti-Ostrich, not involving any other animals/chess pieces. By the way I also made the dimensions of the blocks unknown: you have to determine whether they're 2x3 or 3x2 blocks. Lastly I picked 0-5 as the digits instead of the more conventional 1-6, just to give the good ol' 0 a guest appearance. :idea:

Image

Yep that's it. Just an "egg" at the feet of this big birdie. And the unique solution can just be "hatched" out of it! :idea:

However, I don't guarantee the human-solvability of this puzzle. As usual I just enjoy producing puzzles with the minimum given information and caught this 1-clue beauty by accident! :D

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Last edited by udosuk on Fri Sep 19, 2008 4:33 pm, edited 1 time in total.

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 Post subject: Re: Ostrich Rules
PostPosted: Thu May 15, 2008 4:38 pm 
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Ostrich 1A
A couple of clues added to make it human solvable. Eliminating the wrong cage structure is straightforward - the solution takes a few fishes.

Thanks Matt - it is very neat the way that the size and constraints fit together.



Image


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 Post subject: Re: Ostrich Rules
PostPosted: Fri May 16, 2008 4:37 am 
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HATMAN wrote:
Eliminating the wrong cage structure is straightforward...

This is how I eliminate the wrong cage structure:
After initial singles:
Code:
+--------------+---------------+--------------+
| *1235   2345 | *12345   2345 |    0     345 |
|    0   12345 |  12345  12345 |   1345  1345 |
|   135   1345 |   1345    0   |   1345    2  |
+--------------+---------------+--------------+
|    4   01235 |   1235   1235 |   1235  0135 |
|  1235  01235 |  12345  12345 |  12345  *01  |
| -1235  -1235 |    0     2345 |  12345   345 |
+--------------+---------------+--------------+

r5c6 from {01} => ONC+AO: r6c1 can't be 1
1 @ r1 locked @ r1c13 => AO: r6c2 can't be 1
HS @ r6: r6c5=1 => r5c6=0 => HS @ c6,n3: r2c6=1
HS @ r1: r1c3=1 => HS @ r1: r1c2=2
=> No possible 2s @ r6 => Contradiction!

Won't exactly call this "straightforward"... :shock:

This is my key move to solve it:
Code:
+---------------------+-------------------+
| *1235   2345   1235 |   345     0   345 |
|    0    345    345  |  12345  2345 #135 |
+---------------------+-------------------+
|   35    0135   135  |  01345   345   2  |
|    4   01235   1235 |   0135   35  #135 |
+---------------------+-------------------+
| *1235  12345  12345 |   2345  2345   0  |
|   235   345     0   |   2345    1   345 |
+---------------------+-------------------+

1 @ c1 locked @ r15c1
1 @ c6 locked @ r24c6
=> ONC+AO: r15c1 can't be {12}
=> r15c1 can't have 2 => HS @ c1: r6c1=2

Thanks for making the human solvable version! Very enjoyable! :king:

PS: FYI, without any given clue this puzzle gives 8 solutions, and they're all essentially identical to each other upon rotation or reflection. I'm still searching for an equivalent 9x9 puzzle with an elegant set of rules. :ugeek:

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 Post subject: Re: Ostrich Rules
PostPosted: Sat May 17, 2008 8:58 am 
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With the help of h3lix's (easier) puzzle in here, I realised the correct way to solve these:
Hidden Text:
Just start solving the whole grid as a Latin Square, and then determine the Unknown Blocks later when enough cells are established. :idea:

Therefore Maurice's 3-clue puzzle is completely solvable by pure logic (using the key move I pointed out), which makes it very nice. Thanks again! :dance:

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 Post subject: Re: Ostrich Rules
PostPosted: Fri Sep 19, 2008 4:31 pm 
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Mr. Ostrich is back, and this time he's not alone! :king:

Image

Note this time only 2 simple rules: AO & ONC.

Also note the perfect 180 degree symmetry of the puzzle (flip the pic upside down to see). This is the absolute minimum of symmetrical puzzles as far as I can see. :ugeek:

So Maurice and others, if you want to make a human solvable version, hopefully it can retain this characteristic (or at least keep the clue pattern symmetrical). :alien:

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PostPosted: Fri Sep 19, 2008 5:32 pm 
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Crasy your are :brickwall:

JSudoku wrote:
Recursively Solve done in 1225685 milliseconds (20.4 min!)
37775641 nodes traversed
Unique solution found with 29 guesses

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PostPosted: Fri Sep 19, 2008 8:43 pm 
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He's from Australia and he's 180 degree symmetrical he must be Mr Oztrich rules. :)

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PostPosted: Sat Sep 20, 2008 10:35 am 
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That is a beauty udosuk :salute:

As the 6 & 9 can be superimposed over an EGG's image .... you could could have made an ostrich extend her neck towards that egg as well to make a visual link between the EGG and the ostrich ....

:scratch: bu twhy should we mess with perfection :salute:

tarek


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PostPosted: Sat Sep 20, 2008 11:03 am 
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Jean-Christophe wrote:
Crasy your are :brickwall:

JSudoku wrote:
Recursively Solve done in 1225685 milliseconds (20.4 min!)
37775641 nodes traversed
Unique solution found with 29 guesses

If you swap the 6 & 9 perhaps you'll find a longer solving time and more nodes traversed! :geek:

You can have an alternative puzzle with r1c6=6 & r9c4=9. That way the "eggs" will appear at the feet of the 2 "Oztriches" but I'm not changing the pic now.

Thanks for the compliments guys! :king:

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PostPosted: Sun Sep 21, 2008 1:23 pm 
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Okay, I changed my mind. Here is an alternative version based on tarek's suggestion:

Image

Note the eggs are about to be kicked by the ostriches (and their kicking power is known to be stronger than Tiger Woods' driver). But ostriches are famous for their uncaring about their eggs.

And JC you'll find this one less CPU-demanding than the previous version, although the nodes traversed are still way over the 20-mil mark. :!:

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