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The "Unsolvable" 11

The program is also easily capable of solving all of the so-called "Unsolvable 11" from the SudokuList website using the simple logic heuristics described earlier, see http://www.sudoku.org.uk/bifurcation.htm.

Only puzzles #1 and #7 require Heuristic 1+ to open up to allow chaining up to lengths 4 and 5, respectively.

[See list of heuristics here.]

For the record:

Unsolvable #1

File: u1

Solved in 157 steps.

63 steps with the default settings. Then bumping the 1+ setting to 4 cracks the puzzle wide open.

Unsolvable #2

File: u2

Solved in 173 steps.

Nothing special. Default settings only.

Unsolvable #3

File: u3

Solved in 163 steps.

Nothing special. Default settings only.

Unsolvable #4

File: u4

Solved in 156 steps.

Nothing special. Default settings only.

Unsolvable #5

File: u5

Solved in 156 steps.

Nothing special. Default settings only.

Unsolvable #6

File: u6

Solved in 167 steps.

Nothing special. Default settings only.

Unsolvable #7

File: u7

Solved in 151 steps.

99 steps with default settings. Bump 1+ setting to 5 to crack the puzzle.

Unsolvable #8

File: u8

Solved in 183 steps.

Nothing special. Default settings only.

Unsolvable #9

File: u9

Solved in 174 steps.

Nothing special. Default settings only.

Unsolvable #10

File: u10

Solved in 172 steps.

Nothing special. Default settings only.

Unsolvable #11

File: u11

Solved in 145 steps.

Nothing special. Default settings only.

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