The New Sudoku Players' Forum

by **ravel** » Mon Feb 12, 2007 1:23 pm

Mauricio's puzzle

Code: Select all: 6 . .|. . 2|. 5 9 5 2 .|. 4 .|. 1 . . . 3|5 . .|2 . . -----+-----+----- 3 . .|1 9 4|5 . . . 1 .|6 5 8|. 3 . . . 5|2 7 3|. . 1 -----+-----+----- . . 4|. . 5|1 . . . 3 .|. 2 .|. 4 5 7 5 .|4 . .|. . 8

has 242 minimal sudokus, 62 of them are non isomorphic. Out of those 9 have a rating of 14 points, the rest 13. All have ER 11.0.
The solutions are nearly identical, in the puzzles with 14 points an addiditional step is needed (always r1c2<>5). This is one of them:

Code: Select all: 6.......9.2..4..1...35..2......9.5...1...8.3...5273.....4..51...3..2..4.7..4....8

by **m_b_metcalf** » Mon Feb 12, 2007 7:04 pm

ravel wrote:Wow,
congratulations for the new Explainer record, Mike.

My rating is not so exciting, 16 points, but for the first hard step it needs 6 subnets (!), which i think is a record, too.

Here is a cousin of the first, almost an isomorph, but the central value is a repeat of r3c3 and r7c7, rather than of r1c1 and r9c9:

Code: Select all: 3 . . . . . . . 4 . 8 . 2 . . . 7 . . . 6 . . . 5 . . . 1 . 9 . 8 . . . SE >=11.4 . . . . 6 . . . . . . . . . 7 . 2 . . . 5 . . . 6 . . . 9 . . . 1 . 8 . 4 . . . . . . . 3

It also reaches SE 11.4 then gives "java.lang.OutOfMemoryError: Java heap space".

Both of these puzzles have not only a symmetric clue pattern, but the values themselves also have an extraordinary degree of symmetry: box 1 reflects box 9, two values in box 3 reflect those in box 7, and the the two 'cross-bars' are identical.

Regards,

Mike Metcalf

by **r.e.s.** » Mon Feb 12, 2007 9:56 pm

Just curious ... For either of the 11.4+ puzzles, would anyone care to post the complete candidate grid just at the point where SE goes into never-never-land?

by **ravel** » Tue Feb 13, 2007 11:28 am

As Mike said, this puzzle is very similar to its brother, 16 points and 6 subnets in the first step.

I dont know, which eliminations Sudoku Explainer can make from the starting grid (after 2 hidden pairs):

Code: Select all: *-----------------------------------------------------------------------* | 3 257 1279 | 15678 15789 569 | 28 169 4 | | 159 8 149 | 2 13459 34569 | 139 7 169 | | 1279 247 6 | 13478 134789 349 | 5 139 28 | |-----------------------+-----------------------+-----------------------| | 2567 1 2347 | 9 2345 8 | 347 3456 567 | | 25789 23457 234789 | 1345 6 2345 | 134789 13459 15789 | | 5689 3456 3489 | 1345 1345 7 | 13489 2 15689 | |-----------------------+-----------------------+-----------------------| | 18 237 5 | 3478 234789 2349 | 6 149 1279 | | 267 9 237 | 34567 23457 1 | 247 8 257 | | 4 267 18 | 5678 25789 2569 | 1279 159 3 | *-----------------------------------------------------------------------*

But even with using subnets in contradiction chains my program can only make 11 eliminations of numbers, which would lead to at least one other elimination then.

Code: Select all: 3 subnets, progress 2: r1c4<>6, r9c6<>6, r4c1<>6, r6c9<>6 6 subnets, progress 8: r1c2<>5, r2c3<>4 7 subnets, progress 11: r2c9<>6, r4c8<>6 7 subnets, progress 8: r3c9<>3 8 subnets, progress 8: r8c7<>4, r9c8<>5

Only 8 candidates could be eliminated with a single subnet:

Code: Select all: r3c5<>34, r5c7<>34, r1c5<>5, r5c9<>5, r2c6<>9, r8c4<>7

[Added:] As i saw now, SE found 6 of them (not the two 3's), then got out of memory.

by **Eioru** » Wed Feb 14, 2007 3:11 am

I started from this pattern,

Code: Select all: *.......* .*.*.*.*. ..*...*... .*.*.*.*. ....*.... .*.*.*.*. ..*...*.. .*.*.*.*. *.......*

and the result of finding some hours.
6.......3.4.7.6.1...7.......8.1...2.....4.....2.5.7.9...5...7...1.2...4.3.......6 ER=6.9
6.......3.4.7...1...7.......8.1.9.2.....4.....2.5...9...5...7...1.2.3.4.3.......6 ER=7.2
6.......3.4.2.8.5...1...9...2.8.5.1.....9.....7...4.....2...5...8.4...7.3.......6 ER=7.2
6.......3.4.2.8.5...1...9...2.8.5.1.....9.....7.3.......2...5...8.4...7.3.......6 ER=7.2
3.......8.5...2.7...9...4.....3.4.1.....9.....7.8.6.2...2...1...9.6.8.5.4.......7 ER=7.3
7.......4.9.5.1.8...8...3...5.8.3.6.....4.....4.7.2.9...1...7.....6.8...3.......2 ER=7.4
7.......9.8.3.2.5...6...2...3.9.1.8.....6.....5.2.4.6...2...3...9.5...4.5.......1 ER=8.2
4.......5.8.3.9.....1...2...7.6...8.....9.....3.8.5.9...5...6...4.1.8.5.2.......3 ER=8.3
9.......3...7.3.6...4...5...1...6.8.....5.....9.2.7.....2...1...7.9.8.3.5.......4 ER=8.9
3.......7.4...5.9...2...6.....8.9.1.....2.....8.3.4.5...5...1...9.6.8.4.7.......9 ER=9.0
1.......5.6.8.3.2...2...4...2.5.6.7.....3.....8.1.2.....8...1...7.6...5.4.......9 ER=9.1

continue hoping a result will become this pattern.

Code: Select all: *.......* .*...*.*. ..*...*... ...*.*.*. ....*.... .*.*.*... ..*...*.. .*.*...*. *.......*

by **ravel** » Wed Feb 14, 2007 9:52 am

Hi Eioru,

i am not sure about the purpose of your post. The puzzles are easy (max. 4 points) compared to the hardest and the second pattern is very well searched by JPF and Mike M. So it is unprobable to find any more big nuggets there.

by **coloin** » Wed Feb 14, 2007 4:15 pm

Have we got hard sudokus for all the possible potential patterns with 21 clues and under ?.....

Code: Select all: 21 a133 b322 c333 d333 e233 f132 313 232 303 331 303 323 331 223 033 302 331 232 and others 20 a133 b033 303 322 331 322 19 a222 b123 232 321 222 232

No we hadnt ! - "and others" refered to JPFs and MMs efforts:

Code: Select all: 21 313 151 313 20 313 141 313 19* 313 131 313

Will the 19* of this pattern be difficult ?

Code: Select all: *.......* .*...*.*. ..*...*... .....*.*. ....*.... .*.*..... ..*...*.. .*.*...*. *.......*

by **ravel** » Wed Feb 14, 2007 8:30 pm

coloin wrote:Will the 19* of this pattern be difficult ?

Hard to say, but i dont expect it. Do you remember Nick70's exhaustive search for all sudokus with this pattern, which also looks promisimg ?

Code: Select all: *...*.... ...*...*. ..*...*.. .*...*... *...*...* ...*...*. ..*...*.. .*...*... ....*...*

There are (only) 851 puzzles, and only one is a toughie with 10 steps and ER 9.1:

Code: Select all: 100050000000200030004000600090003000600070005000100070001000200030009000000060001

by **StrmCkr** » Thu Feb 15, 2007 9:08 am

Will the 19* of this pattern be difficult ?

Code: Select all: *.......* .*...*.*. ..*...*... .....*.*. ....*.... .*.*..... ..*...*.. .*.*...*. *.......*

yes they are just as difficult you can mirror the puzzle along the middle column swamping all rows horizontally like this .

and the rating stays the same

Code: Select all: *-----------* |9..|...|..5| |.7.|..1|.2.| |..3|...|8..| |---+---+---| |...|2.7|.4.| |...|.5.|...| |.1.|6..|...| |---+---+---| |..8|...|3..| |.2.|4..|.6.| |5..|...|..9| *-----------*

you can do the same thing on ocean's new's present and christmas as well and the rateing stays the same...

my 2 cents ....(isn't this called automorphes??)

strmckrs

by **Eioru** » Thu Feb 15, 2007 10:45 am

How these two pattern? I feel it's too hard to find one puzzle.

Code: Select all: .....*... ..*.*.*.. .*.*...*. *.....*.. .*..*..*. ..*.....* .*...*.*. ..*.*.*.. ...*.....

Code: Select all: .....*... ..*.*.... ...*...*. *...*.*.. .*.*.*.*. ..*.*...* .*...*... ....*.*.. ...*.....

by **m_b_metcalf** » Thu Feb 15, 2007 2:46 pm

Eioru wrote:How these two pattern? I feel it's too hard to find one puzzle.
Code: Select all
.....*... ..*.*.*.. .*.*...*. *.....*.. .*..*..*. ..*.....* .*...*.*. ..*.*.*.. ...*.....

Well, here's the first:

Code: Select all: . . . . . 9 . . . . . 7 . 1 . 3 . . . 2 . 4 . . . 6 . 8 . . . . . 9 . . . 6 . . 7 . . 5 . . . 3 . . . . . 2 . 8 . . . 6 . 4 . . . 9 . 3 . 1 . . . . . 2 . . . . . SE 9.1

Regards,

Mike Metcalf

by **ravel** » Thu Feb 15, 2007 3:25 pm

Two more:

Code: Select all: .....7.....2.5.9...1.8...3.1.....8...7..9..1...4.....2.6...1.7...9.2.4.....3..... ER 7.2 .....6.....1.9.7...2.8...5.3.....1...8..7..9...6.....2.5...2.8...7.1.3.....9..... ER 9.1

So it seems that this pattern is comparable to many others that follow tso's rule of thumb (high ratings on average).

by **m_b_metcalf** » Thu Feb 15, 2007 9:16 pm

m_b_metcalf wrote:Here is a cousin of the first, almost an isomorph, but the central value is a repeat of r3c3 and r7c7, rather than of r1c1 and r9c9:
Code: Select all
3 . . . . . . . 4 . 8 . 2 . . . 7 . . . 6 . . . 5 . . . 1 . 9 . 8 . . . SE >=11.4 . . . . 6 . . . . . . . . . 7 . 2 . . . 5 . . . 6 . . . 9 . . . 1 . 8 . 4 . . . . . . . 3

It also reaches SE 11.4 then gives "java.lang.OutOfMemoryError: Java heap space".

I have discussed this puzzle privately with the author of Sudoku Explainer, Nicolas Juillerat, who kindly provided the information below.

Regards,

Mike Metcalf

==========================================

A very difficult and interesting puzzle. It seems to require nested chains with multiple inferences. I have not seen this before.

It is still possible to rate this puzzle with the current version of the Sudoku Explainer. But you need to start the .jar file from a command line, and to use the "-Xmx" option to tell the Java VM to use more memory (by default it only uses a fraction of the available memory). For instance:

java -Xmx500m -jar SudokuExplainer.jar

starts the application and tells the Java VM to use at most 500MB. This should be enough to solve the puzzle.

By the way, if you have installed the full Java JDK (not only the JRE), you may want to use the java command from the jdk, and to also add the "-server" option: the GUI gets less responsive but the long analyses run faster (about 2h20 instead of 3h15 on my computer).

Difficulty rating: 11.4

57 x Hidden Single
2 x Direct Hidden Pair
1 x Naked Single
5 x Pointing
2 x Naked Pair
1 x X-Wing
3 x Hidden Pair
2 x Naked Triplet
1 x Swordfish
1 x XY-Wing
1 x BUG type 1
1 x Forcing X-Chain
1 x Bidirectional Cycle
8 x Forcing Chain
2 x Nishio Forcing Chains
14 x Region Forcing Chains
5 x Cell Forcing Chains
1 x Dynamic Cell Forcing Chains
7 x Dynamic Contradiction Forcing Chains
3 x Dynamic Region Forcing Chains
3 x Dynamic Contradiction Forcing Chains (+)
11 x Dynamic Contradiction Forcing Chains (+ Forcing Chains)
2 x Dynamic Region Forcing Chains (+ Forcing Chains)
5 x Dynamic Contradiction Forcing Chains (+ Multiple Forcing Chains)
2 x Dynamic Region Forcing Chains (+ Dynamic Forcing Chains)
4 x Dynamic Contradiction Forcing Chains (+ Dynamic Forcing Chains)

by AW » Sat Feb 17, 2007 5:21 am

{removed}

by **ronk** » Sat Feb 17, 2007 6:33 am

AW wrote:Is my back-door finder broken or does Mike's

Code: Select all
500000009020100070008000300040702000000050000000006010003000800060004020900000005

really not have any strict back-door pairs (that crack the puzzle with only naked or hidden singles remaining) ????

If I understand your meaning of "backdoor pairs" ...

(r1c5=7 and r9c6=8) or (r2c6=9 and r9c8=4) or (r5c8=3 and r7c9=6)

... require only following singles.

The New Sudoku Players' Forum

The hardest sudokus