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

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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)