Analysis of zz-www.sudokuoftheday.co.uk-20060822-absurd-base.sdk

Contents

Sudoku from http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Aug&YEAR=2006

level: medium

Sudoku from http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Aug&YEAR=2006

position: .95..............8.2.....61....9.3....7..4...9...21...8..269..41....39.2....4.6.. initial

Autosolve

position: .95.1......1....98.289...61..2.9.3....7..4..99...21...8.3269..41....39.22.914.6.. autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # D1: 4,6 => CTR => D1: 8
* PRF # D1: 8 => SOL
* PRF # A2: 4,6 => SOL
* PRF # F1: 2,6 => SOL
* DIS # F1: 8 => CTR => F1: 2,6
* DIS # G3: 5,7 => CTR => G3: 4
* DIS # F4: 5,7 => CTR => F4: 6,8
* DIS # H1: 2,4 => CTR => H1: 3,7
* DIS # I9: 5 => CTR => I9: 3,7
* DIS # A4: 4,6 => CTR => A4: 5
* PRF # A4: 5 => SOL
* PRF # B4: 4,6 => SOL
* DIS # B6: 4,6 => CTR => B6: 3,8
* PRF # F4: 5,8 => SOL
* DIS # D5: 5,8 => CTR => D5: 3,6
* DIS # D6: 5,8 => CTR => D6: 3,6,7
* DIS # E8: 7 => CTR => E8: 5,8
* DIS # H7: 1 => CTR => H7: 5,7
* PRF # B4: 4,6 => SOL
* DIS # B6: 4,6 => CTR => B6: 3,8
* DIS # H9: 5,7 => CTR => H9: 3,8
* DIS # I9: 5,7 => CTR => I9: 3
* CNT  22 HDP CHAINS /  47 HYP OPENED

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

Pair Reduction

Pair Reduction

The following important HDP chains were detected:

* DIS # D1: 4,6 => CTR => D1: 8
* PRF D1: 8 => SOL
* STA D1: 8
* CNT   2 HDP CHAINS /   1 HYP OPENED

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

Details

Positions

.95..............8.2.....61....9.3....7..4...9...21...8..269..41....39.2....4.6.. initial
.95.1......1....98.289...61..2.9.3....7..4..99...21...8.3269..41....39.22.914.6.. autosolve
495816237631472598728935461542798316317654829986321745873269154164583972259147683 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (11)
D2: 4,6
F2: 2,6
F3: 5,7
I1: 3,7
C6: 4,6
E5: 5,8
B7: 5,7
B8: 4,6
C8: 4,6
B9: 5,7
G7: 1,7

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
B4,B5: 1.. / B4 = 1  =>  0 pairs (X) / B5 = 1  =>  0 pairs (_)
G7,H7: 1.. / G7 = 1  => 12 pairs (_) / H7 = 1  =>  0 pairs (X)
B4,H4: 1.. / B4 = 1  =>  0 pairs (X) / H4 = 1  =>  0 pairs (_)
G5,G7: 1.. / G5 = 1  =>  0 pairs (X) / G7 = 1  => 12 pairs (_)
F1,F2: 2.. / F1 = 2  =>  0 pairs (X) / F2 = 2  => 11 pairs (_)
G5,H5: 2.. / G5 = 2  =>  0 pairs (X) / H5 = 2  => 12 pairs (_)
F2,G2: 2.. / F2 = 2  => 11 pairs (_) / G2 = 2  =>  0 pairs (X)
H1,H5: 2.. / H1 = 2  =>  0 pairs (X) / H5 = 2  => 12 pairs (_)
E2,E3: 3.. / E2 = 3  => 19 pairs (_) / E3 = 3  => 13 pairs (_)
H1,I1: 3.. / H1 = 3  => 18 pairs (_) / I1 = 3  =>  0 pairs (X)
D5,D6: 3.. / D5 = 3  =>  0 pairs (X) / D6 = 3  =>  0 pairs (_)
H9,I9: 3.. / H9 = 3  =>  0 pairs (X) / I9 = 3  => 18 pairs (_)
A3,E3: 3.. / A3 = 3  => 19 pairs (_) / E3 = 3  => 13 pairs (_)
B6,D6: 3.. / B6 = 3  =>  0 pairs (X) / D6 = 3  =>  0 pairs (_)
H1,H9: 3.. / H1 = 3  => 18 pairs (_) / H9 = 3  =>  0 pairs (X)
I1,I9: 3.. / I1 = 3  =>  0 pairs (X) / I9 = 3  => 18 pairs (_)
D1,D2: 4.. / D1 = 4  =>  0 pairs (X) / D2 = 4  =>  0 pairs (_)
B8,C8: 4.. / B8 = 4  =>  0 pairs (X) / C8 = 4  =>  0 pairs (_)
A3,G3: 4.. / A3 = 4  =>  0 pairs (X) / G3 = 4  => 16 pairs (_)
C6,C8: 4.. / C6 = 4  =>  0 pairs (X) / C8 = 4  =>  0 pairs (_)
G2,G3: 5.. / G2 = 5  => 13 pairs (_) / G3 = 5  =>  0 pairs (X)
A4,A5: 5.. / A4 = 5  =>  0 pairs (*) / A5 = 5  =>  0 pairs (X)
B7,B9: 5.. / B7 = 5  => 13 pairs (_) / B9 = 5  => 16 pairs (_)
E2,G2: 5.. / E2 = 5  =>  0 pairs (X) / G2 = 5  => 13 pairs (_)
B7,H7: 5.. / B7 = 5  => 13 pairs (_) / H7 = 5  => 16 pairs (_)
I4,I6: 6.. / I4 = 6  =>  0 pairs (*) / I6 = 6  =>  0 pairs (X)
B8,C8: 6.. / B8 = 6  =>  0 pairs (*) / C8 = 6  =>  0 pairs (X)
C6,C8: 6.. / C6 = 6  =>  0 pairs (*) / C8 = 6  =>  0 pairs (X)
B7,B9: 7.. / B7 = 7  => 16 pairs (_) / B9 = 7  => 13 pairs (_)
D1,F1: 8.. / D1 = 8  =>  0 pairs (*) / F1 = 8  =>  0 pairs (X)
G5,G6: 8.. / G5 = 8  =>  0 pairs (*) / G6 = 8  =>  0 pairs (X)
H8,H9: 8.. / H8 = 8  =>  0 pairs (X) / H9 = 8  => 22 pairs (_)
F9,H9: 8.. / F9 = 8  =>  0 pairs (X) / H9 = 8  => 22 pairs (_)
E5,E8: 8.. / E5 = 8  =>  0 pairs (X) / E8 = 8  =>  0 pairs (_)
* DURATION: 0:00:45.561777  START: 01:59:08.008883  END: 01:59:53.570660 2019-05-01
* CP COUNT: (34)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (B7,B8,B9,C6,C8,D2,E5,F2,F3,G7,I1)
* .95.1......1....98.289...61..2.9.3....7..4..99...21...8.3269..41....39.22.914.6..
* PAIR D2: 4,6 BLK 2
D1: 4,6,8                                # reduction candidate for 4,6
D1: 4,6 => CTR
* .95.18.37..1..2.98.289...61..2.963.5567384.2993..21..68.3269..41.6..39.22.914.683
D1: 8 => SOLVED
* 495816237631472598728935461542798316317654829986321745873269154164583972259147683
* PAIR D2: 4,6 ROW 2
A2: 4,6,3,7                              # reduction candidate for 4,6
A2: 4,6 => SOLVED
* 495816237631472598728935461542798316317654829986321745873269154164583972259147683
A2: 3,7                                  # 12 pairs
B2: 4,6,3                                # reduction candidate for 4,6
B2: 4,6                                  # 17 pairs
* PAIR F2: 2,6 BLK 2
F1: 2,6,8                                # reduction candidate for 2,6
F1: 2,6 => SOLVED
* 495816237631472598728935461542798316317654829986321745873269154164583972259147683
F1: 8 => CTR
* .95.18.37..1..2.98.289...61..2.963.5567384.2993..21..68.3269..41.6..39.22.914.683
* PAIR F3: 5,7 BLK 2
E2: 5,7,3                                # reduction candidate for 5,7
E2: 5,7                                  # 13 pairs
E3: 5,7,3                                # reduction candidate for 5,7
E3: 5,7                                  # 19 pairs
* PAIR F3: 5,7 ROW 3
G3: 5,7,4                                # reduction candidate for 5,7
G3: 5,7 => CTR
* .95.1..377.1....9842893..61..2.9.3....7.54..99...21...8.3269..41..5839722.9147683
G3: 4                                    # 16 pairs
* PAIR F3: 5,7 COL F
F4: 5,7,6,8                              # reduction candidate for 5,7
F4: 5,7 => CTR
* .9581......14...98.289...61.82.9.31..17.842599..521847853269174146..39.22.914.6..
F4: 6,8                                  # 22 pairs
F9: 5,7,8                                # reduction candidate for 5,7
F9: 5,7                                  # 22 pairs
* PAIR I1: 3,7 BLK 3
H1: 3,7,2,4                              # reduction candidate for 3,7
H1: 2,4 => CTR
* .9581...3..14...98.289...61.82.9.31..17.842599..521847853269174146..39822.914863.
H1: 3,7                                  # 17 pairs
* PAIR I1: 3,7 COL I
I9: 3,7,5                                # reduction candidate for 3,7
I9: 5 => CTR
* .9581...3..14...98.289...61.82.9.31..17.842599..521847853269174146..3982279148635
I9: 3,7                                  # 16 pairs
* PAIR C6: 4,6 BLK 4
A4: 4,6,5                                # reduction candidate for 4,6
A4: 4,6 => CTR
* .95.1......1....98.289...61.82.9.31.517.84..99...218..8.3269..41....39.22.914.6..
A4: 5 => SOLVED
* 495816237631472598728935461542798316317654829986321745873269154164583972259147683
B4: 4,6,1,8                              # reduction candidate for 4,6
B4: 4,6 => SOLVED
* 495816237631472598728935461542798316317654829986321745873269154164583972259147683
B4: 1,8                                  # 12 pairs
B6: 4,6,3,8                              # reduction candidate for 4,6
B6: 4,6 => CTR
* .9581.....314...98.2893..615.27983.6387654..99..3218..8.3269..41..5839722.9147683
B6: 3,8                                  # 12 pairs
* PAIR E5: 5,8 BLK 5
D4: 5,8,6,7                              # reduction candidate for 5,8
D4: 5,8                                  # 18 pairs
F4: 5,8,6,7                              # reduction candidate for 5,8
F4: 5,8 => SOLVED
* 495816237631472598728935461542798316317654829986321745873269154164583972259147683
F4: 6,7                                  # 12 pairs
D5: 5,8,3,6                              # reduction candidate for 5,8
D5: 5,8 => CTR
* .95.1......1....98.289...61..2.9.3....7..4..99..321...8.3269..41....39.22.914.6..
D5: 3,6                                  # 12 pairs
D6: 5,8,3,6,7                            # reduction candidate for 5,8
D6: 5,8 => CTR
* .95.1......1....98.289...61..2.9.3.5567384..9934.21...8.3269..41....39.22.914.6..
D6: 3,6,7                                # 13 pairs
* PAIR E5: 5,8 COL E
E8: 5,8,7                                # reduction candidate for 5,8
E8: 7 => CTR
* .95.1......1....98.289.7.61.82.9.31..17.842599..5218478532691741.48739.22.914.6..
E8: 5,8                                  # 16 pairs
* PAIR B7: 5,7 ROW 7
H7: 5,7,1                                # reduction candidate for 5,7
H7: 1 => CTR
* .95.1......1....98.289...61.12.9.3...87.541299...218..8532697141..5.39.227914.6..
H7: 5,7                                  # 12 pairs
* PAIR B8: 4,6 COL B
B2: 4,6,3                                # reduction candidate for 4,6
B2: 4,6                                  # 17 pairs
B4: 4,6,1,8                              # reduction candidate for 4,6
B4: 4,6 => SOLVED
* 495816237631472598728935461542798316317654829986321745873269154164583972259147683
B4: 1,8                                  # 12 pairs
B6: 4,6,3,8                              # reduction candidate for 4,6
B6: 4,6 => CTR
* .9581.....314...98.2893..615.27983.6387654..99..3218..8.3269..41..5839722.9147683
B6: 3,8                                  # 12 pairs
* PAIR B9: 5,7 ROW 9
F9: 5,7,8                                # reduction candidate for 5,7
F9: 5,7                                  # 22 pairs
H9: 5,7,3,8                              # reduction candidate for 5,7
H9: 5,7 => CTR
* .9581..37..14...98.289...61.82.9.31..17.84.299...21...8.3269..41....39822.91486.3
H9: 3,8                                  # 12 pairs
I9: 5,7,3                                # reduction candidate for 5,7
I9: 5,7 => CTR
* .9581...3..14...98.289...61.82.9.31..17.842599..521847853269174146..39822.914863.
I9: 3                                    # 18 pairs
* PAIR G7: 1,7 BLK 9
H7: 1,7,5                                # reduction candidate for 1,7
H7: 5                                    # 16 pairs
H7: 1,7                                  # 13 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060822-absurd-base-pr-000.dot
* REASONING
* DIS # D1: 4,6 => CTR => D1: 8
* PRF # D1: 8 => SOL
* PRF # A2: 4,6 => SOL
* PRF # F1: 2,6 => SOL
* DIS # F1: 8 => CTR => F1: 2,6
* DIS # G3: 5,7 => CTR => G3: 4
* DIS # F4: 5,7 => CTR => F4: 6,8
* DIS # H1: 2,4 => CTR => H1: 3,7
* DIS # I9: 5 => CTR => I9: 3,7
* DIS # A4: 4,6 => CTR => A4: 5
* PRF # A4: 5 => SOL
* PRF # B4: 4,6 => SOL
* DIS # B6: 4,6 => CTR => B6: 3,8
* PRF # F4: 5,8 => SOL
* DIS # D5: 5,8 => CTR => D5: 3,6
* DIS # D6: 5,8 => CTR => D6: 3,6,7
* DIS # E8: 7 => CTR => E8: 5,8
* DIS # H7: 1 => CTR => H7: 5,7
* PRF # B4: 4,6 => SOL
* DIS # B6: 4,6 => CTR => B6: 3,8
* DIS # H9: 5,7 => CTR => H9: 3,8
* DIS # I9: 5,7 => CTR => I9: 3
* CNT  22 HDP CHAINS /  47 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (B7,B8,B9,C6,C8,D2,E5,F2,F3,G7,I1)
* .95.1......1....98.289...61..2.9.3....7..4..99...21...8.3269..41....39.22.914.6..
* PAIR D2: 4,6 BLK 2
D1: 4,6,8                                # reduction candidate for 4,6
D1: 4,6 => CTR
* .95.18.37..1..2.98.289...61..2.963.5567384.2993..21..68.3269..41.6..39.22.914.683
D1: 8 => SOLVED
* 495816237631472598728935461542798316317654829986321745873269154164583972259147683
* DURATION: 0:00:02.550023  START: 02:00:28.280544  END: 02:00:30.830567 2019-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060822-absurd-base-pr-001.dot
* REASONING
* DIS # D1: 4,6 => CTR => D1: 8
* PRF D1: 8 => SOL
* STA D1: 8
* CNT   2 HDP CHAINS /   1 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Aug&YEAR=2006, 20060822, absurd

Solution

position: 495816237631472598728935461542798316317654829986321745873269154164583972259147683 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:

* DIS # D1: 4,6 => CTR => D1: 8
* PRF # D1: 8 => SOL
* PRF # A2: 4,6 => SOL
* INC # A2: 3,7 => UNS
* INC # B2: 4,6 => UNS
* PRF # F1: 2,6 => SOL
* DIS # F1: 8 => CTR => F1: 2,6
* INC # E2: 5,7 => UNS
* INC # E3: 5,7 => UNS
* DIS # G3: 5,7 => CTR => G3: 4
* INC # G3: 4 => UNS
* DIS # F4: 5,7 => CTR => F4: 6,8
* INC # F4: 6,8 => UNS
* INC # F9: 5,7 => UNS
* INC # H1: 3,7 => UNS
* DIS # H1: 2,4 => CTR => H1: 3,7
* INC # I9: 3,7 => UNS
* DIS # I9: 5 => CTR => I9: 3,7
* DIS # A4: 4,6 => CTR => A4: 5
* PRF # A4: 5 => SOL
* PRF # B4: 4,6 => SOL
* INC # B4: 1,8 => UNS
* DIS # B6: 4,6 => CTR => B6: 3,8
* INC # B6: 3,8 => UNS
* INC # D4: 5,8 => UNS
* PRF # F4: 5,8 => SOL
* INC # F4: 6,7 => UNS
* DIS # D5: 5,8 => CTR => D5: 3,6
* INC # D5: 3,6 => UNS
* DIS # D6: 5,8 => CTR => D6: 3,6,7
* INC # D6: 3,6,7 => UNS
* INC # E8: 5,8 => UNS
* DIS # E8: 7 => CTR => E8: 5,8
* INC # H7: 5,7 => UNS
* DIS # H7: 1 => CTR => H7: 5,7
* INC # B2: 4,6 => UNS
* PRF # B4: 4,6 => SOL
* INC # B4: 1,8 => UNS
* DIS # B6: 4,6 => CTR => B6: 3,8
* INC # B6: 3,8 => UNS
* INC # F9: 5,7 => UNS
* DIS # H9: 5,7 => CTR => H9: 3,8
* INC # H9: 3,8 => UNS
* DIS # I9: 5,7 => CTR => I9: 3
* INC # I9: 3 => UNS
* INC # H7: 1,7 => UNS
* INC # H7: 5 => UNS
* CNT  47 HDP CHAINS /  47 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* DIS # D1: 4,6 => CTR => D1: 8
* PRF D1: 8 => SOL
* STA D1: 8
* CNT   2 HDP CHAINS /   1 HYP OPENED