Analysis of zz-www.sudokuwiki.org-0080-base.sdk

Contents

Sudoku from http://www.sudokuwiki.org/Print_Weekly_Sudoku.asp?unsolvable=80

level: medium

Sudoku from http://www.sudokuwiki.org/Print_Weekly_Sudoku.asp?unsolvable=80

position: 1....7..5.3.6..7....7....4..52......6...8...2......43..6....1....5..3.2.9..1....8 initial

Autosolve

position: 1.6..7..5.3.6..7....7....4..52...8..6...8...2......43..6....1...15..3.2.9..1....8 autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* PRF # G3: 2,3 => SOL
* DIS # H2: 1 => CTR => H2: 8,9
* DIS # H2: 1,9 => CTR => H2: 8
* DIS # G3: 2 => CTR => G3: 3,6
* DIS # A7: 7,8 => CTR => A7: 2,3,4
* DIS # C7: 3,4 => CTR => C7: 8
* PRF # C5: 3,4 => SOL
* DIS # C5: 1,9 => CTR => C5: 3,4
* CNT   8 HDP CHAINS /  30 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 # G3: 2,3 => SOL
* STA G3: 2,3
* CNT   1 HDP CHAINS /   1 HYP OPENED

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

Details

Positions

1....7..5.3.6..7....7....4..52......6...8...2......43..6....1....5..3.2.9..1....8 initial
1.6..7..5.3.6..7....7....4..52...8..6...8...2......43..6....1...15..3.2.9..1....8 autosolve
186437295439625781527918346352741869674389512891256437268594173715863924943172658 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (8)
G1: 2,3
H1: 8,9
I2: 1,9
I3: 3,6
A6: 7,8
G5: 5,9
C9: 3,4
G8: 6,9

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
E3,F3: 1.. / E3 = 1  =>  8 pairs (_) / F3 = 1  =>  9 pairs (_)
H2,I2: 1.. / H2 = 1  =>  0 pairs (X) / I2 = 1  =>  9 pairs (_)
C5,C6: 1.. / C5 = 1  =>  0 pairs (X) / C6 = 1  =>  8 pairs (_)
G1,G3: 2.. / G1 = 2  =>  8 pairs (_) / G3 = 2  =>  0 pairs (X)
A7,B9: 2.. / A7 = 2  => 11 pairs (_) / B9 = 2  => 15 pairs (_)
A4,C5: 3.. / A4 = 3  =>  9 pairs (_) / C5 = 3  =>  0 pairs (X)
I7,G9: 3.. / I7 = 3  =>  0 pairs (*) / G9 = 3  =>  0 pairs (X)
C5,D5: 3.. / C5 = 3  =>  0 pairs (X) / D5 = 3  =>  9 pairs (_)
C9,G9: 3.. / C9 = 3  =>  0 pairs (*) / G9 = 3  =>  0 pairs (X)
A4,A7: 3.. / A4 = 3  =>  9 pairs (_) / A7 = 3  =>  0 pairs (X)
I3,I7: 3.. / I3 = 3  => 12 pairs (_) / I7 = 3  =>  0 pairs (*)
I7,I8: 4.. / I7 = 4  => 12 pairs (_) / I8 = 4  => 11 pairs (_)
A2,A3: 5.. / A2 = 5  =>  9 pairs (_) / A3 = 5  =>  8 pairs (_)
G5,H5: 5.. / G5 = 5  =>  8 pairs (_) / H5 = 5  =>  0 pairs (X)
G5,G9: 5.. / G5 = 5  =>  8 pairs (_) / G9 = 5  =>  0 pairs (X)
G3,I3: 6.. / G3 = 6  => 12 pairs (_) / I3 = 6  =>  0 pairs (*)
H4,H9: 6.. / H4 = 6  => 12 pairs (_) / H9 = 6  => 13 pairs (_)
H1,H2: 8.. / H1 = 8  =>  0 pairs (X) / H2 = 8  =>  8 pairs (_)
A8,D8: 8.. / A8 = 8  =>  0 pairs (X) / D8 = 8  =>  9 pairs (_)
G5,G8: 9.. / G5 = 9  =>  0 pairs (X) / G8 = 9  =>  8 pairs (_)
* DURATION: 0:00:27.887257  START: 04:52:19.862170  END: 04:52:47.749427 2017-05-01
* CP COUNT: (20)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A6,C9,G1,G5,G8,H1,I2,I3)
* 1.6..7..5.3.6..7....7....4..52...8..6...8...2......43..6....1...15..3.2.9..1....8
* PAIR G1: 2,3 BLK 3
G3: 2,3,6                                # reduction candidate for 2,3
G3: 2,3 => SOLVED
* 186437295439625781527918346352741869674389512891256437268594173715863924943172658
G3: 6                                    # 12 pairs
* PAIR G1: 2,3 ROW 1
D1: 2,3,4,8,9                            # reduction candidate for 2,3
D1: 2,3                                  # 10 pairs
E1: 2,3,4,9                              # reduction candidate for 2,3
E1: 2,3                                  #  9 pairs
* PAIR H1: 8,9 BLK 3
H2: 8,9,1                                # reduction candidate for 8,9
H2: 1 => CTR
* 1.6.372854386..719527...643352...89.64.38.572.8.5..43.263...15.815.6392.9741..368
H2: 8,9                                  #  9 pairs
* PAIR H1: 8,9 ROW 1
B1: 8,9,2,4                              # reduction candidate for 8,9
B1: 8,9                                  #  9 pairs
D1: 8,9,2,3,4                            # reduction candidate for 8,9
D1: 8,9                                  # 10 pairs
* PAIR I2: 1,9 BLK 3
H2: 1,9,8                                # reduction candidate for 1,9
H2: 1,9 => CTR
* 1.6.372854386..7..527...643352...8..64.38.572.8.5..43.263...15.815.6392.9741..368
H2: 8                                    #  8 pairs
* PAIR I2: 1,9 COL I
I4: 1,9,6,7                              # reduction candidate for 1,9
I4: 1,9                                  # 10 pairs
I6: 1,9,6,7                              # reduction candidate for 1,9
I6: 1,9                                  # 13 pairs
* PAIR I3: 3,6 BLK 3
G3: 3,6,2                                # reduction candidate for 3,6
G3: 2 => CTR
* 1.6..73.5.396.87....7.31246352...86.674389512891...437.68...1.37158.39249.31..6.8
G3: 3,6                                  #  8 pairs
* PAIR A6: 7,8 BLK 4
B6: 7,8,9                                # reduction candidate for 7,8
B6: 9                                    # 12 pairs
B6: 7,8                                  # 12 pairs
* PAIR A6: 7,8 COL A
A7: 7,8,2,3,4                            # reduction candidate for 7,8
A7: 7,8 => CTR
* 1.6..7..5.3.6..7....7....4.352...8..6..38...28.....43.768...1.34158.3.2.9231....8
A7: 2,3,4                                #  8 pairs
A8: 7,8,4                                # reduction candidate for 7,8
A8: 7,8                                  # 11 pairs
* PAIR G5: 5,9 BLK 6
H5: 5,9,1,7                              # reduction candidate for 5,9
H5: 5,9                                  # 11 pairs
H5: 1,7                                  #  9 pairs
* PAIR C9: 3,4 BLK 7
A7: 3,4,2,7,8                            # reduction candidate for 3,4
A7: 3,4                                  # 15 pairs
C7: 3,4,8                                # reduction candidate for 3,4
C7: 3,4 => CTR
* 1.6.372.543.6..7..527...643352...8..64.38.5727..5..43.263...15.815.6392.9741..368
C7: 8                                    # 11 pairs
* PAIR C9: 3,4 COL C
C5: 3,4,1,9                              # reduction candidate for 3,4
C5: 3,4 => SOLVED
* 186437295439625781527918346352741869674389512891256437268594173715863924943172658
C5: 1,9 => CTR
* 1.6.372.543.6..7..527...643352...8..64.38.572...5..43.263...15.815.6392.9741..368
* PAIR G8: 6,9 BLK 9
I8: 6,9,4,7                              # reduction candidate for 6,9
I8: 6,9                                  # 15 pairs
I8: 4,7                                  #  9 pairs
* PAIR G8: 6,9 ROW 8
E8: 6,9,4,7                              # reduction candidate for 6,9
E8: 4,7                                  # 14 pairs
E8: 6,9                                  # 10 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuwiki.org-0080-base-pr-000.dot
* REASONING
* PRF # G3: 2,3 => SOL
* DIS # H2: 1 => CTR => H2: 8,9
* DIS # H2: 1,9 => CTR => H2: 8
* DIS # G3: 2 => CTR => G3: 3,6
* DIS # A7: 7,8 => CTR => A7: 2,3,4
* DIS # C7: 3,4 => CTR => C7: 8
* PRF # C5: 3,4 => SOL
* DIS # C5: 1,9 => CTR => C5: 3,4
* CNT   8 HDP CHAINS /  30 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A6,C9,G1,G5,G8,H1,I2,I3)
* 1.6..7..5.3.6..7....7....4..52...8..6...8...2......43..6....1...15..3.2.9..1....8
* PAIR G1: 2,3 BLK 3
G3: 2,3,6                                # reduction candidate for 2,3
G3: 2,3 => SOLVED
* 186437295439625781527918346352741869674389512891256437268594173715863924943172658
* DURATION: 0:00:02.800826  START: 04:53:10.081967  END: 04:53:12.882793 2017-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuwiki.org-0080-base-pr-001.dot
* REASONING
* PRF # G3: 2,3 => SOL
* STA G3: 2,3
* CNT   1 HDP CHAINS /   1 HYP OPENED

Header Info

http://www.sudokuwiki.org/Print_Weekly_Sudoku.asp?unsolvable=80

Solution

position: 186437295439625781527918346352741869674389512891256437268594173715863924943172658 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 # G3: 2,3 => SOL
* INC # G3: 6 => UNS
* INC # D1: 2,3 => UNS
* INC # E1: 2,3 => UNS
* INC # H2: 8,9 => UNS
* DIS # H2: 1 => CTR => H2: 8,9
* INC # B1: 8,9 => UNS
* INC # D1: 8,9 => UNS
* DIS # H2: 1,9 => CTR => H2: 8
* INC # H2: 8 => UNS
* INC # I4: 1,9 => UNS
* INC # I6: 1,9 => UNS
* INC # G3: 3,6 => UNS
* DIS # G3: 2 => CTR => G3: 3,6
* INC # B6: 7,8 => UNS
* INC # B6: 9 => UNS
* DIS # A7: 7,8 => CTR => A7: 2,3,4
* INC # A7: 2,3,4 => UNS
* INC # A8: 7,8 => UNS
* INC # H5: 5,9 => UNS
* INC # H5: 1,7 => UNS
* INC # A7: 3,4 => UNS
* DIS # C7: 3,4 => CTR => C7: 8
* INC # C7: 8 => UNS
* PRF # C5: 3,4 => SOL
* DIS # C5: 1,9 => CTR => C5: 3,4
* INC # I8: 6,9 => UNS
* INC # I8: 4,7 => UNS
* INC # E8: 6,9 => UNS
* INC # E8: 4,7 => UNS
* CNT  30 HDP CHAINS /  30 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* PRF # G3: 2,3 => SOL
* STA G3: 2,3
* CNT   1 HDP CHAINS /   1 HYP OPENED