## SE rating for overlapping Sudoku puzzles - suggestion

Programs which generate, solve, and analyze Sudoku puzzles

### Re: SE rating for overlapping Sudoku puzzles - suggestion

Hajime wrote:Let's try an easy samurai that can be solved with singles only. But neither subgrids can be solved individually.

George-NJ3H's samurai posted here:
Code: Select all
`..1..9......286.....4...3.95.9..........1...4....6..2..6.5........1.....97....... ED=1.5/1.2/1.2...7.8.9.1.....47..4.........2.9...7....21...3.8.....4.2.............8.5...2.4... ED=1.5/1.2/1.2.......2....9........37..........3.66.8..........2...7...6..........5........1... ED=2.3/1.2/1.2..5..9.....7..........6.......8.....1.....4.35..9.6....1.7...4.......162.2..8.... ED=1.5/1.2/1.2......3.8...5.4......2..4..8.5.6..4.....2..7.9......8..63.....7.....9....7...6..1 ED=2.0/1.2/1.2ED=2.3/1.2/1.2781349256395286741624751389519472638236815974847963125163528497452197863978634512235748196186935472947612358612493587754821963398576214523187649471369825869254731497168523863952471512374869249517386678493215135826947321689754986745132754231698865479321247135986391268754972843615186527493534916278613752849758394162429681537754691328132584796698273415825967143346128579917345682463812957581739264279456831Solved.`

1to9only

Posts: 4152
Joined: 04 April 2018

### Re: SE rating for overlapping Sudoku puzzles - suggestion

So the overall SE is the maximum of the subgrid's SE.
I think that is not fair...

Hajime

Posts: 1316
Joined: 20 April 2018
Location: Fryslân

### Re: SE rating for overlapping Sudoku puzzles - suggestion

The samurai rating is ED=HighestER/LowestEP/LowestED, as in another of nj3h's samurai posted here:
Code: Select all
`983.........6....4.4.8.5..........52....28.....5...7...2...1.......9....8.7.5.... ED=1.5/1.2/1.2...6..9..3.6..1....5....463...2.4..6....9.1..58...6......5...2........59....2..3. ED=4.4/1.5/1.5............4.9......8.7....62.3..........172.51.7.......7.4......2.5............ ED=1.5/1.2/1.25.9.7........9.....7...3.....2...3......41..........27.5.6.8......3....6826...... ED=2.0/1.2/1.2....2..1........92...8...6.58...1.......6.5.....7.5..6.7....4533.4..7......1..9.. ED=1.5/1.2/1.2ED=4.4/1.2/1.2983214675152679834746835291398167452471528963265943718629381547534792186817456329247635918396481572158972463971254386632897145584316297819563724723148659465729831547623819186459723329817465762138594938546172451972386213764958874295631695381247589476213361592874274183695492867351735241968618935427953618742147329586826754139958326714631574892247819365586431279713962548429785136172698453394257681865143927Solved.`

1to9only

Posts: 4152
Joined: 04 April 2018

### Re: SE rating for overlapping Sudoku puzzles - suggestion

1to9only wrote:The samurai rating is ED=HighestER/LowestEP/LowestED

Who decided this, can that be changed or discussed at least?
A Samurai is more difficult that its toughest sub grid.
And a Sumo is more difficult than a Samurai

Hajime

Posts: 1316
Joined: 20 April 2018
Location: Fryslân

### Re: SE rating for overlapping Sudoku puzzles - suggestion

Hajime wrote:
1to9only wrote:The samurai rating is ED=HighestER/LowestEP/LowestED

Who decided this, can that be changed or discussed at least?
A Samurai is more difficult that its toughest sub grid.

Surely that depends on whether the Samurai can be solved by iterating over the five subgrids or whether, as in ruud's hardest, a global 21x21 approach is required.

Regards,

Mike Metcalf

m_b_metcalf
2017 Supporter

Posts: 13539
Joined: 15 May 2006
Location: Berlin

### Re: SE rating for overlapping Sudoku puzzles - suggestion

Hajime wrote:Who decided this, can that be changed or discussed at least?

Any rating system is subjective... I've given a few examples of how my own SamuraiExplainer is progressing, I've currently hit a few snags rating the harder samurais, so it's likely to be mothballed for a few months before I have another hack at it.

1to9only

Posts: 4152
Joined: 04 April 2018

### Re: SE rating for overlapping Sudoku puzzles - suggestion

SE is unsuitable for solving (rating) the harder samurai puzzles, this is mainly because SE expects solving 9x9 sudokus having single solutions, whereas in samurais the subgrids will often have multiple solutions, and m_b_metcalf's suggestion of a 21x21 grid is the better approach.

Here is another of nj3h's samurai posted here:
Code: Select all
`.72.....5.9.1.5.......8.2..6...92...1......8.......6329.1...........8.....3..4......83......7...8....2.5..6..2.4......4....5.773...6..9......97....641......9..........2................1.....42.....9...1..8..8...6.........3........6......7........5.....5.4..2...6.3...........4.9.156.........3....8.3..4.65..61.7........2.84....6....4...38.......7..1..65...7.8......26.........5.8.1.....6.......92..2.56...`

This is correctly solved up to this point:
Code: Select all
`.72.....5.9.125....1..8.2..63..92...12.....8...9..16329.12........9.8.2.2.3.14... ED=2.6/1.2/1.2...83.7....716.8....275..6..2.4......4....5.773...6..9......97.97.641...2..9..... ED=2.6/1.2/1.2.....2....2....97.....1.2...42.....9...1..8..8...6.....64..3........6.2.285741396 ED=3.6/1.2/1.2...538.64584.62...6.349.2853.8..4.96156.8.4...4.3.6..8832.4.657461875...795623841 1.0, Hidden Single: R9C2: 9 in block...6....4.2.38..65...7.51.865...728....5.26..2...6..5.8.12..5.6.......929.2.56... ED=1.7/1.2/1.2`

SE is solving subgrid 4, and r9c2=9 is the last solving step.
Code: Select all
`+-------------+-------------+-------------+| 29  12  79  | 5   3   8   | 17  6   4   || 5   8   4   | 17  6   2   | 39  17  39  || 6   17  3   | 4   9   17  | 2   8   5   |+-------------+-------------+-------------+| 3   27  8   | 27  15  4   | 15  9   6   || 1   5   6   | 279 8   79  | 4   237 23  || 29  4   79  | 3   15  6   | 157 12  8   |+-------------+-------------+-------------+| 8   3   2   | 19  4   19  | 6   5   7   || 4   6   1   | 8   7   5   | 39  23  239 || 7   9   5   | 6   2   3   | 8   4   1   |+-------------+-------------+-------------+`

Then SE finds this:
Code: Select all
`4.5, Unique Rectangle type 1: Cells R2C7,R2C9,R8C9,R8C7 on 3, 9`

SE then removes candidates 3,9 from r8c9, and it later solves the hidden single 2 in r8c9 - this leads to an unsolvable samurai.
.

1to9only

Posts: 4152
Joined: 04 April 2018

### Re: SE rating for overlapping Sudoku puzzles - suggestion

I'm away from home at the moment and cannot access my samurai solver, but I can investigate sub-puzzle 4, and note that, if one looks for all its solutions and retains the common clues, then one gets
Code: Select all
` . . . 5 3 8 . 6 4 5 8 4 . 6 2 . . . 6 . 3 4 9 . 2 8 5 3 . 8 . . 4 . 9 6 1 5 6 . 8 . 4 . . . 4 . 3 . 6 . . 8 8 3 2 . 4 . 6 5 7 4 6 1 8 7 5 . . . 7 9 5 6 2 3 8 4 1No. of givens = 53brute found 3 solution(s) Common clues (74): 9 2 7 5 3 8 1 6 4 5 8 4 1 6 2 . 7 . 6 1 3 4 9 7 2 8 5 3 7 8 2 1 4 5 9 6 1 5 6 7 8 9 4 . . 2 4 9 3 5 6 7 1 8 8 3 2 9 4 1 6 5 7 4 6 1 8 7 5 . . . 7 9 5 6 2 3 8 4 1`

thereby providing two more values in an overlap region and thus, presumably, advancing the puzzle towards a final solution. However, none of that fits into an SE rating framework

Regards,

Mike

m_b_metcalf
2017 Supporter

Posts: 13539
Joined: 15 May 2006
Location: Berlin

### Re: SE rating for overlapping Sudoku puzzles - suggestion

I notice that SudokuSolver solves this samurai by taking a different solving path:
Code: Select all
`Switched to grid: 4133. Grid:04 Unique Corner on {15} at r4c5, r4c7, r6c5, r6c7133a. Cell r6c7 cannot contain {15}134. Grid:04 Naked Single 7 found at r6c7135. Grid:04 Naked Single 1 found at r1c7`

By grid4 r1c7=1, switching to grid3 solves grid4 r2c7=9 (this is grid3 r8c1=9) and the grid4 UR goes away.
.

1to9only

Posts: 4152
Joined: 04 April 2018

### Re: SE rating for overlapping Sudoku puzzles - suggestion

1to9only wrote:Here is another of nj3h's samurai posted here:
Code: Select all
`.72.....5.9.1.5.......8.2..6...92...1......8.......6329.1...........8.....3..4......83......7...8....2.5..6..2.4......4....5.773...6..9......97....641......9..........2................1.....42.....9...1..8..8...6.........3........6......7........5.....5.4..2...6.3...........4.9.156.........3....8.3..4.65..61.7........2.84....6....4...38.......7..1..65...7.8......26.........5.8.1.....6.......92..2.56...`

This has now been solved by tweaking SE to find the 1,5 UR first, and disabling BUG (as it screws up grid3 later):
Code: Select all
`.72.....5.9.1.5.......8.2..6...92...1......8.......6329.1...........8.....3..4... ED=3.0/1.2/1.2...83......7...8....2.5..6..2.4......4....5.773...6..9......97....641......9..... ED=4.0/1.2/1.2.....2................1.....42.....9...1..8..8...6.........3........6......7..... ED=3.6/1.2/1.2...5.....5.4..2...6.3...........4.9.156.........3....8.3..4.65..61.7........2.84. ED=4.5/1.2/1.2...6....4...38.......7..1..65...7.8......26.........5.8.1.....6.......92..2.56... ED=4.2/1.2/1.2ED=4.5/1.2/1.2872369145496125873315487269638792514124653987759841632941276358567938421283514796614832795597164832382759164829475316146398527735216489461523978978641253253987641358972461421635978796418253542387619637129845819564732164293587973856124285741396927538164584162973613497285378214596156789432249356718832941657461875329795623841587621934124389765396745128659417283748532619213968457831294576465173892972856341Solved.`

1to9only

Posts: 4152
Joined: 04 April 2018

### Re: SE rating for overlapping Sudoku puzzles - suggestion

After each candidate elimination (and cell solving) in overlapping areas you need to start all over again with all the methods in ascending SE order for involved subgrids. See my code on 16 sept of this thread.
Pretty slow algorithm that probably can be optimised.

Hajime

Posts: 1316
Joined: 20 April 2018
Location: Fryslân

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