Analysis of zz-sudoku-de-636873-base.sdk

Contents

Original Sudoku

level: medium

Original Sudoku

position: 8..6.9..3..........62...75..9.7.1.6..8..5..4..3.2.8.1..78...23..........4..8.5..9 initial

Autosolve

position: 8..6.9.23...5...9.9624.375..9.7.1.6..8..56.4..3.2.8.1..78..423...9....8.4..8.5.79 autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* PRF # B1: 1,4 => SOL
* DIS # B1: 5 => CTR => B1: 1,4
* DIS # G2: 1,4 => CTR => G2: 6,8
* DIS # I2: 1,4 => CTR => I2: 6,8
* DIS # C1: 1,7 => CTR => C1: 5
* PRF # C1: 5 => SOL
* DIS # E2: 2,7 => CTR => E2: 1,8
* DIS # E2: 2,7 => CTR => E2: 1,8
* DIS # G2: 1,4 => CTR => G2: 6,8
* DIS # I2: 1,4 => CTR => I2: 6,8
* PRF # B1: 1,4 => SOL
* DIS # B1: 5 => CTR => B1: 1,4
* DIS # G8: 1,4 => CTR => G8: 5,6
* DIS # I2: 1,8 => CTR => I2: 4,6
* DIS # I4: 2,5 => CTR => I4: 8
* DIS # C6: 4,5 => CTR => C6: 6,7
* PRF # C6: 6,7 => SOL
* DIS # A5: 2 => CTR => A5: 1,7
* DIS # C1: 1,7 => CTR => C1: 5
* PRF # C1: 5 => SOL
* PRF # C2: 1,7 => SOL
* DIS # C2: 3 => CTR => C2: 1,7
* DIS # A5: 1 => CTR => A5: 2,7
* PRF # A6: 5,7 => SOL
* DIS # A6: 6 => CTR => A6: 5,7
* DIS # C6: 5,7 => CTR => C6: 4,6
* DIS # B8: 1,2 => CTR => B8: 5
* PRF # B8: 5 => SOL
* DIS # A8: 5,6 => CTR => A8: 1,3
* DIS # E8: 3,6 => CTR => E8: 2,7
* DIS # I7: 1,6 => CTR => I7: 5
* DIS # I8: 1,6 => CTR => I8: 4,5
* DIS # C9: 1,6 => CTR => C9: 3
* PRF # C9: 3 => SOL
* DIS # G2: 1,6 => CTR => G2: 4,8
* CNT  35 HDP CHAINS /  56 HYP OPENED

See Appendix: Full HDP Chains for full list of HDP chains.

Pair Reduction

Pair Reduction

The following important HDP chains were detected:

* PRF # B1: 1,4 => SOL
* STA B1: 1,4
* CNT   1 HDP CHAINS /   1 HYP OPENED

See Appendix: Full HDP Chains for full list of HDP chains.

Details

Positions

8..6.9..3..........62...75..9.7.1.6..8..5..4..3.2.8.1..78...23..........4..8.5..9 initial
8..6.9.23...5...9.9624.375..9.7.1.6..8..56.4..3.2.8.1..78..423...9....8.4..8.5.79 autosolve
815679423347512896962483751294731568781956342536248917678194235159327684423865179 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (22)
B2: 1,4
E1: 1,7
F2: 2,7
E3: 1,8
G1: 1,4
I3: 1,8
A4: 2,5
C4: 4,5
C5: 1,7
E4: 3,4
D5: 3,9
E6: 4,9
G5: 3,9
I5: 2,7
G6: 5,9
I6: 5,7
B9: 1,2
D7: 1,9
E7: 6,9
D8: 1,3
F8: 2,7
G9: 1,6

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
A5,C5: 1.. / A5 = 1  =>  0 pairs (X) / C5 = 1  => 25 pairs (_)
D7,D8: 1.. / D7 = 1  =>  0 pairs (*) / D8 = 1  =>  0 pairs (X)
E3,I3: 1.. / E3 = 1  =>  0 pairs (X) / I3 = 1  => 22 pairs (_)
E2,F2: 2.. / E2 = 2  =>  0 pairs (X) / F2 = 2  => 20 pairs (_)
A4,A5: 2.. / A4 = 2  => 22 pairs (_) / A5 = 2  =>  0 pairs (X)
I4,I5: 2.. / I4 = 2  =>  0 pairs (X) / I5 = 2  => 22 pairs (_)
B8,B9: 2.. / B8 = 2  =>  0 pairs (X) / B9 = 2  => 24 pairs (_)
A4,I4: 2.. / A4 = 2  => 22 pairs (_) / I4 = 2  =>  0 pairs (X)
A5,I5: 2.. / A5 = 2  =>  0 pairs (X) / I5 = 2  => 22 pairs (_)
B9,E9: 2.. / B9 = 2  => 24 pairs (_) / E9 = 2  =>  0 pairs (X)
F2,F8: 2.. / F2 = 2  => 20 pairs (_) / F8 = 2  =>  0 pairs (X)
A2,C2: 3.. / A2 = 3  =>  0 pairs (*) / C2 = 3  =>  0 pairs (X)
E4,D5: 3.. / E4 = 3  =>  0 pairs (*) / D5 = 3  =>  0 pairs (X)
G4,G5: 3.. / G4 = 3  =>  0 pairs (X) / G5 = 3  =>  0 pairs (_)
A8,C9: 3.. / A8 = 3  =>  0 pairs (X) / C9 = 3  =>  0 pairs (_)
E4,G4: 3.. / E4 = 3  =>  0 pairs (*) / G4 = 3  =>  0 pairs (X)
D5,G5: 3.. / D5 = 3  =>  0 pairs (X) / G5 = 3  =>  0 pairs (_)
C9,E9: 3.. / C9 = 3  =>  0 pairs (*) / E9 = 3  =>  0 pairs (X)
A2,A8: 3.. / A2 = 3  =>  0 pairs (*) / A8 = 3  =>  0 pairs (X)
C2,C9: 3.. / C2 = 3  =>  0 pairs (X) / C9 = 3  =>  0 pairs (_)
D5,D8: 3.. / D5 = 3  =>  0 pairs (X) / D8 = 3  =>  0 pairs (_)
B1,B2: 4.. / B1 = 4  =>  0 pairs (X) / B2 = 4  => 21 pairs (_)
C4,C6: 4.. / C4 = 4  =>  0 pairs (*) / C6 = 4  =>  0 pairs (X)
E4,E6: 4.. / E4 = 4  =>  0 pairs (X) / E6 = 4  =>  0 pairs (_)
G8,I8: 4.. / G8 = 4  =>  0 pairs (X) / I8 = 4  => 22 pairs (_)
B1,G1: 4.. / B1 = 4  =>  0 pairs (X) / G1 = 4  => 21 pairs (_)
C4,E4: 4.. / C4 = 4  =>  0 pairs (*) / E4 = 4  =>  0 pairs (X)
C6,E6: 4.. / C6 = 4  =>  0 pairs (X) / E6 = 4  =>  0 pairs (_)
I2,I8: 4.. / I2 = 4  =>  0 pairs (X) / I8 = 4  => 22 pairs (_)
B1,C1: 5.. / B1 = 5  =>  0 pairs (X) / C1 = 5  =>  0 pairs (_)
A7,I7: 5.. / A7 = 5  =>  0 pairs (X) / I7 = 5  => 21 pairs (_)
B1,B8: 5.. / B1 = 5  =>  0 pairs (X) / B8 = 5  =>  0 pairs (_)
G2,I2: 6.. / G2 = 6  =>  0 pairs (X) / I2 = 6  => 23 pairs (_)
A6,C6: 6.. / A6 = 6  =>  0 pairs (X) / C6 = 6  =>  0 pairs (_)
C6,C9: 6.. / C6 = 6  =>  0 pairs (*) / C9 = 6  =>  0 pairs (X)
I5,I6: 7.. / I5 = 7  =>  0 pairs (X) / I6 = 7  => 22 pairs (_)
E8,F8: 7.. / E8 = 7  =>  0 pairs (X) / F8 = 7  => 20 pairs (_)
C1,E1: 7.. / C1 = 7  =>  0 pairs (X) / E1 = 7  => 23 pairs (_)
F2,F8: 7.. / F2 = 7  =>  0 pairs (X) / F8 = 7  => 20 pairs (_)
E2,E3: 8.. / E2 = 8  =>  0 pairs (X) / E3 = 8  => 22 pairs (_)
G4,I4: 8.. / G4 = 8  =>  0 pairs (X) / I4 = 8  => 21 pairs (_)
E3,I3: 8.. / E3 = 8  => 22 pairs (_) / I3 = 8  =>  0 pairs (X)
G2,G4: 8.. / G2 = 8  => 21 pairs (_) / G4 = 8  =>  0 pairs (X)
D5,E6: 9.. / D5 = 9  =>  0 pairs (*) / E6 = 9  =>  0 pairs (X)
G5,G6: 9.. / G5 = 9  =>  0 pairs (X) / G6 = 9  =>  0 pairs (_)
D7,E7: 9.. / D7 = 9  =>  0 pairs (X) / E7 = 9  =>  0 pairs (_)
D5,G5: 9.. / D5 = 9  =>  0 pairs (*) / G5 = 9  =>  0 pairs (X)
E6,G6: 9.. / E6 = 9  =>  0 pairs (X) / G6 = 9  =>  0 pairs (_)
D5,D7: 9.. / D5 = 9  =>  0 pairs (*) / D7 = 9  =>  0 pairs (X)
E6,E7: 9.. / E6 = 9  =>  0 pairs (X) / E7 = 9  =>  0 pairs (_)
* DURATION: 0:01:32.729637  START: 07:28:45.068709  END: 07:30:17.798346 2017-05-01
* CP COUNT: (50)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A4,B2,B9,C4,C5,D5,D7,D8,E1,E3,E4,E6,E7,F2,F8,G1,G5,G6,G9,I3,I5,I6)
* 8..6.9.23...5...9.9624.375..9.7.1.6..8..56.4..3.2.8.1..78..423...9....8.4..8.5.79
* PAIR B2: 1,4 BLK 1
B1: 1,4,5                                # reduction candidate for 1,4
B1: 1,4 => SOLVED
* 815679423347512896962483751294731568781956342536248917678194235159327684423865179
B1: 5 => CTR
* 85.6.9423.4.5...9.9624.375.29.7.1.6..8..56.4263.2.8.17578..423.3.91..5844168.5.79
* PAIR B2: 1,4 ROW 2
G2: 1,4,6,8                              # reduction candidate for 1,4
G2: 1,4 => CTR
* 8..6.9.23...5...969624.3758.9.7.186..8..5634..3.2.891..78.9423...93..5844.38.5.79
G2: 6,8                                  # 23 pairs
I2: 1,4,6,8                              # reduction candidate for 1,4
I2: 1,4 => CTR
* 85.6.942334.582691962413758.9.73186..8.95634..3624891.578194236619327584423865179
I2: 6,8                                  # 23 pairs
* PAIR E1: 1,7 BLK 2
E2: 1,7,2,8                              # reduction candidate for 1,7
E2: 2,8                                  # 23 pairs
E2: 1,7                                  # 21 pairs
* PAIR E1: 1,7 ROW 1
C1: 1,7,5                                # reduction candidate for 1,7
C1: 1,7 => CTR
* 85.6.9423.4.5...9.9624.375.29.7.1.6..8..56.4263.2.8.17578..423.3.91..5844168.5.79
C1: 5 => SOLVED
* 815679423347512896962483751294731568781956342536248917678194235159327684423865179
* PAIR F2: 2,7 BLK 2
E2: 2,7,1,8                              # reduction candidate for 2,7
E2: 2,7 => CTR
* 8576194231435...9.962483751.9.7.1.6..81.56.4..3.2.8.1..7819423.3.9....844..8.5.79
E2: 1,8                                  # 23 pairs
* PAIR E3: 1,8 BLK 2
E2: 1,8,2,7                              # reduction candidate for 1,8
E2: 2,7 => CTR
* 8576194231435...9.962483751.9.7.1.6..81.56.4..3.2.8.1..7819423.3.9....844..8.5.79
E2: 1,8                                  # 23 pairs
* PAIR G1: 1,4 BLK 3
G2: 1,4,6,8                              # reduction candidate for 1,4
G2: 1,4 => CTR
* 8..6.9.23...5...969624.3758.9.7.186..8..5634..3.2.891..78.9423...93..5844.38.5.79
G2: 6,8                                  # 23 pairs
I2: 1,4,6,8                              # reduction candidate for 1,4
I2: 1,4 => CTR
* 85.6.942334.582691962413758.9.73186..8.95634..3624891.578194236619327584423865179
I2: 6,8                                  # 23 pairs
* PAIR G1: 1,4 ROW 1
B1: 1,4,5                                # reduction candidate for 1,4
B1: 1,4 => SOLVED
* 815679423347512896962483751294731568781956342536248917678194235159327684423865179
B1: 5 => CTR
* 85.6.9423.4.5...9.9624.375.29.7.1.6..8..56.4263.2.8.17578..423.3.91..5844168.5.79
* PAIR G1: 1,4 COL G
G8: 1,4,5,6                              # reduction candidate for 1,4
G8: 1,4 => CTR
* 8..6.9423.4.5.2896962483751294731568.8.956342536248917678.94235..9.671844..825679
G8: 5,6                                  # 23 pairs
* PAIR I3: 1,8 BLK 3
G2: 1,8,4,6                              # reduction candidate for 1,8
G2: 1,8                                  # 23 pairs
I2: 1,8,4,6                              # reduction candidate for 1,8
I2: 1,8 => CTR
* 85.6.942334.5..69.9624.375..9.73186..8.95634..3624891.5781942366193..584423865179
I2: 4,6                                  # 23 pairs
* PAIR A4: 2,5 ROW 4
I4: 2,5,8                                # reduction candidate for 2,5
I4: 2,5 => CTR
* 85.6.942334.5...9.9624.375..9.73186..8.95634..3624891.5781942366193..584423865179
I4: 8                                    # 21 pairs
* PAIR C4: 4,5 BLK 4
C6: 4,5,6,7                              # reduction candidate for 4,5
C6: 4,5 => CTR
* 8..6.9423.435...9.9624.375..9.741368.8.356942634298517.789642353591..684426835179
C6: 6,7 => SOLVED
* 815679423347512896962483751294731568781956342536248917678194235159327684423865179
* PAIR C5: 1,7 BLK 4
A5: 1,7,2                                # reduction candidate for 1,7
A5: 2 => CTR
* 8..6.9.23...5...9.9624.375..9.7.1.6.281.56.47.3.2.8.15578..423...9....8.4..8.5.79
A5: 1,7                                  # 22 pairs
* PAIR C5: 1,7 COL C
C1: 1,7,5                                # reduction candidate for 1,7
C1: 1,7 => CTR
* 85.6.9423.4.5...9.9624.375.29.7.1.6..8..56.4263.2.8.17578..423.3.91..5844168.5.79
C1: 5 => SOLVED
* 815679423347512896962483751294731568781956342536248917678194235159327684423865179
C2: 1,7,3                                # reduction candidate for 1,7
C2: 1,7 => SOLVED
* 815679423347512896962483751294731568781956342536248917678194235159327684423865179
C2: 3 => CTR
* 8..6.9423.435..896962483751295741368.8.356942634298517.7896423.3.91...8.426835179
* PAIR I5: 2,7 ROW 5
A5: 2,7,1                                # reduction candidate for 2,7
A5: 1 => CTR
* 8..679.237.35.2.9.9624.375.29.741368187356942.342985175789642313.91.7.8.4..835.79
A5: 2,7                                  # 25 pairs
* PAIR I6: 5,7 ROW 6
A6: 5,7,6                                # reduction candidate for 5,7
A6: 5,7 => SOLVED
* 815679423347512896962483751294731568781956342536248917678194235159327684423865179
A6: 6 => CTR
* 8..6.9423.435...9.9624.375..9.741368.8.356942634298517.789642353591..684426835179
C6: 5,7,4,6                              # reduction candidate for 5,7
C6: 5,7 => CTR
* 8..6.9.23...5...9.9624.375..94731.6..8.95634.63.24891..78194236..9367.8.4..8.5.79
C6: 4,6                                  # 23 pairs
* PAIR B9: 1,2 BLK 7
B8: 1,2,5                                # reduction candidate for 1,2
B8: 1,2 => CTR
* 85.6.9423.4.5...9.9624.375.29.7.1.6..8..56.4263.2.8.17578..423.3.91..5844168.5.79
B8: 5 => SOLVED
* 815679423347512896962483751294731568781956342536248917678194235159327684423865179
* PAIR D8: 1,3 ROW 8
A8: 1,3,5,6                              # reduction candidate for 1,3
A8: 5,6 => CTR
* 8.5679.233.75.2.9.9624.375..94731.6.18.95634..3624891..7819423...93...8.4.38.5.79
A8: 1,3                                  # 24 pairs
* PAIR F8: 2,7 BLK 8
E8: 2,7,3,6                              # reduction candidate for 2,7
E8: 3,6 => CTR
* 85.6.942334.5.2.969624.375..9.7.1.6.187.56.42.36248917.78.9423..29.67.84413825679
E8: 2,7                                  # 24 pairs
* PAIR G9: 1,6 BLK 9
I7: 1,6,5                                # reduction candidate for 1,6
I7: 1,6 => CTR
* 85.6.9423.4.5...9.9624.375.29.7.1.65.8..56.42635248917578.94236..9.675844.68.5.79
I7: 5                                    # 21 pairs
G8: 1,6,4,5                              # reduction candidate for 1,6
G8: 1,6                                  # 21 pairs
I8: 1,6,4,5                              # reduction candidate for 1,6
I8: 1,6 => CTR
* 845679123.1.5.26949624.375..9.7.1.6..8..56.4..3.2.8.1..78..423...9...48.4..8.5.79
I8: 4,5                                  # 23 pairs
* PAIR G9: 1,6 ROW 9
C9: 1,6,3                                # reduction candidate for 1,6
C9: 1,6 => CTR
* 8..6.9423.435..896962483751295741368.8.356942634298517.7896423.3.91...8.426835179
C9: 3 => SOLVED
* 815679423347512896962483751294731568781956342536248917678194235159327684423865179
* PAIR G9: 1,6 COL G
G2: 1,6,4,8                              # reduction candidate for 1,6
G2: 1,6 => CTR
* 85.6.942334.5...9.9624.375..9.73186..8.95634..3624891.5781942366193..584423865179
G2: 4,8                                  # 24 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-sudoku-de-636873-base-pr-000.dot
* REASONING
* PRF # B1: 1,4 => SOL
* DIS # B1: 5 => CTR => B1: 1,4
* DIS # G2: 1,4 => CTR => G2: 6,8
* DIS # I2: 1,4 => CTR => I2: 6,8
* DIS # C1: 1,7 => CTR => C1: 5
* PRF # C1: 5 => SOL
* DIS # E2: 2,7 => CTR => E2: 1,8
* DIS # E2: 2,7 => CTR => E2: 1,8
* DIS # G2: 1,4 => CTR => G2: 6,8
* DIS # I2: 1,4 => CTR => I2: 6,8
* PRF # B1: 1,4 => SOL
* DIS # B1: 5 => CTR => B1: 1,4
* DIS # G8: 1,4 => CTR => G8: 5,6
* DIS # I2: 1,8 => CTR => I2: 4,6
* DIS # I4: 2,5 => CTR => I4: 8
* DIS # C6: 4,5 => CTR => C6: 6,7
* PRF # C6: 6,7 => SOL
* DIS # A5: 2 => CTR => A5: 1,7
* DIS # C1: 1,7 => CTR => C1: 5
* PRF # C1: 5 => SOL
* PRF # C2: 1,7 => SOL
* DIS # C2: 3 => CTR => C2: 1,7
* DIS # A5: 1 => CTR => A5: 2,7
* PRF # A6: 5,7 => SOL
* DIS # A6: 6 => CTR => A6: 5,7
* DIS # C6: 5,7 => CTR => C6: 4,6
* DIS # B8: 1,2 => CTR => B8: 5
* PRF # B8: 5 => SOL
* DIS # A8: 5,6 => CTR => A8: 1,3
* DIS # E8: 3,6 => CTR => E8: 2,7
* DIS # I7: 1,6 => CTR => I7: 5
* DIS # I8: 1,6 => CTR => I8: 4,5
* DIS # C9: 1,6 => CTR => C9: 3
* PRF # C9: 3 => SOL
* DIS # G2: 1,6 => CTR => G2: 4,8
* CNT  35 HDP CHAINS /  56 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A4,B2,B9,C4,C5,D5,D7,D8,E1,E3,E4,E6,E7,F2,F8,G1,G5,G6,G9,I3,I5,I6)
* 8..6.9.23...5...9.9624.375..9.7.1.6..8..56.4..3.2.8.1..78..423...9....8.4..8.5.79
* PAIR B2: 1,4 BLK 1
B1: 1,4,5                                # reduction candidate for 1,4
B1: 1,4 => SOLVED
* 815679423347512896962483751294731568781956342536248917678194235159327684423865179
* DURATION: 0:00:02.359262  START: 07:31:15.985364  END: 07:31:18.344626 2017-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-sudoku-de-636873-base-pr-001.dot
* REASONING
* PRF # B1: 1,4 => SOL
* STA B1: 1,4
* CNT   1 HDP CHAINS /   1 HYP OPENED

Header Info

http://www.sudokus.de/636873.html
sehr schwierig

--------------------------------------------------
level: medium

* PAIR REDUCTION ..
* ROUND 1: 8..6.9.23...5...9.9624.375..9.7.1.6..8..56.4..3.2.8.1..78..423...9....8.4..8.5.79
B2: 1,4
B1: 1,4,5                                # reduction candidate for 1,4
B1: 1,4 => SOLVED
* 815679423347512896962483751294731568781956342536248917678194235159327684423865179
* SOLVED!

--------------------------------------------------
* AUTO ..
H1 = 2                # set value
D2 = 5                # set value
H2 = 9                # set value
A3 = 9                # set value
H9 = 7                # set value
H8: 8                 # naked single
C8: 9..               # hidden single
C8 = 9                # set value
H8 = 8                # set value
Q1: 3.. = A2,C2: 3.. => E2,F2 != 3
Q4: 2.. = A4,A5: 2.. => A8 != 2
Q4: 4.. = C4,C6: 4.. => C1,C2 != 4
Q5: 4.. = E4,E6: 4.. => E1,E2,E3,E7,E8 != 4
F5: 6                 # naked single
D5,G5: 3,9.. => F5 != 3,9 # naked pair
F2,F8: 2,7.. => F2,F8 != 3,4,6 # hidden pair
F3: 3                 # naked single
F2,F3,F8: 2,3,7.. => F3 != 4 # hidden triple
D3: 4..               # hidden single
F7: 4..               # hidden single
D3 = 4                # set value
F3 = 3                # set value
F5 = 6                # set value
F7: 4                 # naked single
F7 = 4                # set value
Q2: 1.. = E1,E2,E3: 1.. => E7,E8,E9 != 1
* UNSOLVED!

|:step:| 00
--------------------------------------------------

--------------------------------------------------
* DISABLE VALUE:: B8 != 5
B1: 5..               # hidden single
* AUTO ..
B1 = 5                # set value
B2: 4..               # hidden single
G1: 4..               # hidden single
G1 = 4                # set value
B2 = 4                # set value
I8: 4..               # hidden single
I8 = 4                # set value
Q1,Q4: 1.. => A7,A8,C9 != 1
A4: 2                 # naked single
Q7: 5.. = A7,A8: 5.. => A4,A6 != 5
A4 = 2                # set value
I5: 2..               # hidden single
I5 = 2                # set value
I6: 7..               # hidden single
I6 = 7                # set value
A6: 6                 # naked single
A6 = 6                # set value
A7: 5                 # naked single
A7 = 5                # set value
A8: 3                 # naked single
A8 = 3                # set value
C9: 6                 # naked single
D8: 1                 # naked single
D8 = 1                # set value
D7: 9                 # naked single
B8: 2                 # naked single
C9 = 6                # set value
G9: 1                 # naked single
G9 = 1                # set value
I7: 6                 # naked single
B9: 2                 # naked single
C2: 3..               # hidden single
E9: 3..               # hidden single
G8: 5..               # hidden single
D5: 3..               # hidden single
I4: 5..               # hidden single
B8,B9 = 2 => CTR
B8,B9 = 2 => CTR
* CTR!

=> B8 = 5

|:step:| 01
--------------------------------------------------

Solution

position: 815679423347512896962483751294731568781956342536248917678194235159327684423865179 solved
Solution

See section Pair Reduction for the HDP chains leading to this result.

Appendix: Full HDP Chains

A1. Pair Reduction Analysis

Full list of HDP chains traversed:

* PRF # B1: 1,4 => SOL
* DIS # B1: 5 => CTR => B1: 1,4
* DIS # G2: 1,4 => CTR => G2: 6,8
* INC # G2: 6,8 => UNS
* DIS # I2: 1,4 => CTR => I2: 6,8
* INC # I2: 6,8 => UNS
* INC # E2: 1,7 => UNS
* INC # E2: 2,8 => UNS
* DIS # C1: 1,7 => CTR => C1: 5
* PRF # C1: 5 => SOL
* DIS # E2: 2,7 => CTR => E2: 1,8
* INC # E2: 1,8 => UNS
* INC # E2: 1,8 => UNS
* DIS # E2: 2,7 => CTR => E2: 1,8
* DIS # G2: 1,4 => CTR => G2: 6,8
* INC # G2: 6,8 => UNS
* DIS # I2: 1,4 => CTR => I2: 6,8
* INC # I2: 6,8 => UNS
* PRF # B1: 1,4 => SOL
* DIS # B1: 5 => CTR => B1: 1,4
* DIS # G8: 1,4 => CTR => G8: 5,6
* INC # G8: 5,6 => UNS
* INC # G2: 1,8 => UNS
* DIS # I2: 1,8 => CTR => I2: 4,6
* INC # I2: 4,6 => UNS
* DIS # I4: 2,5 => CTR => I4: 8
* INC # I4: 8 => UNS
* DIS # C6: 4,5 => CTR => C6: 6,7
* PRF # C6: 6,7 => SOL
* INC # A5: 1,7 => UNS
* DIS # A5: 2 => CTR => A5: 1,7
* DIS # C1: 1,7 => CTR => C1: 5
* PRF # C1: 5 => SOL
* PRF # C2: 1,7 => SOL
* DIS # C2: 3 => CTR => C2: 1,7
* INC # A5: 2,7 => UNS
* DIS # A5: 1 => CTR => A5: 2,7
* PRF # A6: 5,7 => SOL
* DIS # A6: 6 => CTR => A6: 5,7
* DIS # C6: 5,7 => CTR => C6: 4,6
* INC # C6: 4,6 => UNS
* DIS # B8: 1,2 => CTR => B8: 5
* PRF # B8: 5 => SOL
* INC # A8: 1,3 => UNS
* DIS # A8: 5,6 => CTR => A8: 1,3
* INC # E8: 2,7 => UNS
* DIS # E8: 3,6 => CTR => E8: 2,7
* DIS # I7: 1,6 => CTR => I7: 5
* INC # I7: 5 => UNS
* INC # G8: 1,6 => UNS
* DIS # I8: 1,6 => CTR => I8: 4,5
* INC # I8: 4,5 => UNS
* DIS # C9: 1,6 => CTR => C9: 3
* PRF # C9: 3 => SOL
* DIS # G2: 1,6 => CTR => G2: 4,8
* INC # G2: 4,8 => UNS
* CNT  56 HDP CHAINS /  56 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* PRF # B1: 1,4 => SOL
* STA B1: 1,4
* CNT   1 HDP CHAINS /   1 HYP OPENED