Analysis of zz-www.sudokuoftheday.co.uk-20060815-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: .8.6.49.5....1.......9.274..4.3...98...4....1..2.9....87.....54..4...8..9..8..17. initial

Autosolve

position: 2876349154.9.1..8....98274..4.3...98.984....1..2.984.787..69.54..4...8.99..84.17. autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # I2: 3,6 => CTR => I2: 2
* DIS # B9: 3,6 => CTR => B9: 2,5
* DIS # D8: 5,7 => CTR => D8: 1,2
* DIS # F4: 5,7 => CTR => F4: 1,6
* DIS # F5: 5,7 => CTR => F5: 6
* DIS # I2: 3,6 => CTR => I2: 2
* DIS # I9: 2 => CTR => I9: 3,6
* DIS # F4: 6,7 => CTR => F4: 1,5
* DIS # D8: 1,5 => CTR => D8: 2,7
* DIS # H5: 3,6 => CTR => H5: 2
* DIS # H8: 2 => CTR => H8: 3,6
* DIS # D8: 5,7 => CTR => D8: 1,2
* DIS # D8: 5,7 => CTR => D8: 1,2
* DIS # E4: 5,7 => CTR => E4: 2
* DIS # F8: 3,5 => CTR => F8: 1,7
* DIS # B9: 3,5 => CTR => B9: 2,6
* CNT  16 HDP CHAINS /  59 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 # I2: 3,6 => CTR => I2: 2
* DIS I2: 2 # D8: 5,7 => CTR => D8: 1,2
* PRF I2: 2 + D8: 1,2 => SOL
* STA I2: 2 + D8: 1,2
* CNT   3 HDP CHAINS /  13 HYP OPENED

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

Details

Positions

.8.6.49.5....1.......9.274..4.3...98...4....1..2.9....87.....54..4...8..9..8..17. initial
2876349154.9.1..8....98274..4.3...98.984....1..2.984.787..69.54..4...8.99..84.17. autosolve
287634915439715682651982743746321598598476321312598467873169254164257839925843176 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (11)
B2: 3,6
D2: 5,7
F2: 5,7
I3: 3,6
D6: 1,5
H6: 3,6
C7: 1,3
D7: 1,2
E8: 5,7
F9: 3,5
G7: 2,3

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
F4,D6: 1.. / F4 = 1  => 15 pairs (_) / D6 = 1  =>  0 pairs (X)
C7,D7: 1.. / C7 = 1  => 12 pairs (_) / D7 = 1  =>  0 pairs (*)
F4,F8: 1.. / F4 = 1  => 15 pairs (_) / F8 = 1  =>  0 pairs (X)
G2,I2: 2.. / G2 = 2  =>  0 pairs (X) / I2 = 2  => 13 pairs (_)
E4,E5: 2.. / E4 = 2  => 13 pairs (_) / E5 = 2  =>  0 pairs (X)
B8,B9: 2.. / B8 = 2  =>  0 pairs (X) / B9 = 2  => 13 pairs (_)
D7,D8: 2.. / D7 = 2  => 12 pairs (_) / D8 = 2  =>  0 pairs (*)
E4,G4: 2.. / E4 = 2  => 13 pairs (_) / G4 = 2  =>  0 pairs (X)
D7,G7: 2.. / D7 = 2  => 12 pairs (_) / G7 = 2  =>  0 pairs (*)
B9,I9: 2.. / B9 = 2  => 13 pairs (_) / I9 = 2  =>  0 pairs (X)
H5,H8: 2.. / H5 = 2  => 14 pairs (_) / H8 = 2  =>  0 pairs (X)
I2,I9: 2.. / I2 = 2  => 13 pairs (_) / I9 = 2  =>  0 pairs (X)
F8,F9: 3.. / F8 = 3  =>  0 pairs (X) / F9 = 3  => 13 pairs (_)
C7,G7: 3.. / C7 = 3  =>  0 pairs (*) / G7 = 3  =>  0 pairs (X)
D2,F2: 5.. / D2 = 5  =>  0 pairs (X) / F2 = 5  => 13 pairs (_)
G4,G5: 5.. / G4 = 5  => 13 pairs (_) / G5 = 5  => 15 pairs (_)
F4,F5: 6.. / F4 = 6  =>  0 pairs (X) / F5 = 6  => 12 pairs (_)
H8,I9: 6.. / H8 = 6  => 17 pairs (_) / I9 = 6  => 12 pairs (_)
D2,F2: 7.. / D2 = 7  => 13 pairs (_) / F2 = 7  =>  0 pairs (X)
A4,A5: 7.. / A4 = 7  => 12 pairs (_) / A5 = 7  => 14 pairs (_)
D2,D8: 7.. / D2 = 7  => 13 pairs (_) / D8 = 7  =>  0 pairs (X)
* DURATION: 0:00:24.294173  START: 01:48:24.254686  END: 01:48:48.548859 2019-05-01
* CP COUNT: (21)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (B2,C7,D2,D6,D7,E8,F2,F9,G7,H6,I3)
* 2876349154.9.1..8....98274..4.3...98.984....1..2.984.787..69.54..4...8.99..84.17.
* PAIR B2: 3,6 BLK 1
A3: 3,6,1,5                              # reduction candidate for 3,6
A3: 3,6                                  # 14 pairs
B3: 3,6,1,5                              # reduction candidate for 3,6
B3: 3,6                                  # 17 pairs
C3: 3,6,1,5                              # reduction candidate for 3,6
C3: 3,6                                  # 14 pairs
* PAIR B2: 3,6 ROW 2
G2: 3,6,2                                # reduction candidate for 3,6
G2: 3,6                                  # 13 pairs
I2: 3,6,2                                # reduction candidate for 3,6
I2: 3,6 => CTR
* 2876349154.9.1.28....98274..4.32..983984...21..2.98437871269354524.738699..845172
I2: 2                                    # 13 pairs
* PAIR B2: 3,6 COL B
B6: 3,6,1,5                              # reduction candidate for 3,6
B6: 3,6                                  # 15 pairs
B8: 3,6,1,2,5                            # reduction candidate for 3,6
B8: 3,6                                  # 17 pairs
B9: 3,6,2,5                              # reduction candidate for 3,6
B9: 3,6 => CTR
* 2876349154.9.1.28....98274..4.32..983984...21..2.98437871269354524.738699..845172
B9: 2,5                                  # 12 pairs
* PAIR D2: 5,7 COL D
D8: 5,7,1,2                              # reduction candidate for 5,7
D8: 5,7 => CTR
* 287634915469.1.283.1398274614.327.9879845...1..21984.7871269354..4..18699..843172
D8: 1,2                                  # 15 pairs
* PAIR F2: 5,7 COL F
F4: 5,7,1,6                              # reduction candidate for 5,7
F4: 5,7 => CTR
* 2876349154.9.1..8..1398274614.3..6987984.65.1..21984.7871269354..4..18.99..84317.
F4: 1,6                                  # 12 pairs
F5: 5,7,6                                # reduction candidate for 5,7
F5: 5,7 => CTR
* 2876349154.9.1..8..13982746145376298.984....1..21984.7871269354..4..18.99..84317.
F5: 6                                    # 12 pairs
F8: 5,7,1,3                              # reduction candidate for 5,7
F8: 5,7                                  # 15 pairs
* PAIR I3: 3,6 BLK 3
G2: 3,6,2                                # reduction candidate for 3,6
G2: 3,6                                  # 13 pairs
I2: 3,6,2                                # reduction candidate for 3,6
I2: 3,6 => CTR
* 2876349154.9.1.28....98274..4.32..983984...21..2.98437871269354524.738699..845172
I2: 2                                    # 13 pairs
* PAIR I3: 3,6 ROW 3
A3: 3,6,1,5                              # reduction candidate for 3,6
A3: 3,6                                  # 14 pairs
B3: 3,6,1,5                              # reduction candidate for 3,6
B3: 3,6                                  # 17 pairs
C3: 3,6,1,5                              # reduction candidate for 3,6
C3: 3,6                                  # 14 pairs
* PAIR I3: 3,6 COL I
I9: 3,6,2                                # reduction candidate for 3,6
I9: 2 => CTR
* 2876349154.9.1.28....98274..4.32..983984...21..2.98437871269354524.738699..845172
I9: 3,6                                  # 13 pairs
* PAIR D6: 1,5 BLK 5
F4: 1,5,6,7                              # reduction candidate for 1,5
F4: 6,7 => CTR
* 2876349154.9.1..8..1398274614.3...987984...31..2198467871269354..4..18.99..84317.
F4: 1,5                                  # 17 pairs
* PAIR D6: 1,5 ROW 6
A6: 1,5,3,6                              # reduction candidate for 1,5
A6: 1,5                                  # 15 pairs
B6: 1,5,3,6                              # reduction candidate for 1,5
B6: 1,5                                  # 13 pairs
* PAIR D6: 1,5 COL D
D8: 1,5,2,7                              # reduction candidate for 1,5
D8: 1,5 => CTR
* 287634915469715283..3982746.4.32..98.984...216.2.98437871269354..4...8699..843172
D8: 2,7                                  # 12 pairs
* PAIR H6: 3,6 BLK 6
G5: 3,6,2,5                              # reduction candidate for 3,6
G5: 3,6                                  # 15 pairs
H5: 3,6,2                                # reduction candidate for 3,6
H5: 3,6 => CTR
* 287634915439517682...982743.4.3...98.984.6.313521984.787.269354..4...829923845176
H5: 2                                    # 14 pairs
* PAIR H6: 3,6 ROW 6
A6: 3,6,1,5                              # reduction candidate for 3,6
A6: 3,6                                  # 13 pairs
B6: 3,6,1,5                              # reduction candidate for 3,6
B6: 3,6                                  # 15 pairs
* PAIR H6: 3,6 COL H
H8: 3,6,2                                # reduction candidate for 3,6
H8: 2 => CTR
* 287634915439517682...982743.4.3...98.984.6.313521984.787.269354..4...829923845176
H8: 3,6                                  # 14 pairs
* PAIR C7: 1,3 BLK 7
A8: 1,3,5,6                              # reduction candidate for 1,3
A8: 1,3                                  # 13 pairs
B8: 1,3,2,5,6                            # reduction candidate for 1,3
B8: 1,3                                  # 16 pairs
* PAIR C7: 1,3 COL C
C3: 1,3,5,6                              # reduction candidate for 1,3
C3: 1,3                                  # 14 pairs
C3: 5,6                                  # 12 pairs
* PAIR D7: 1,2 BLK 8
D8: 1,2,5,7                              # reduction candidate for 1,2
D8: 5,7 => CTR
* 287634915469.1.283.1398274614.327.9879845...1..21984.7871269354..4..18699..843172
D8: 1,2                                  # 15 pairs
* PAIR E8: 5,7 BLK 8
D8: 5,7,1,2                              # reduction candidate for 5,7
D8: 5,7 => CTR
* 287634915469.1.283.1398274614.327.9879845...1..21984.7871269354..4..18699..843172
D8: 1,2                                  # 15 pairs
F8: 5,7,1,3                              # reduction candidate for 5,7
F8: 5,7                                  # 15 pairs
* PAIR E8: 5,7 COL E
E4: 5,7,2                                # reduction candidate for 5,7
E4: 5,7 => CTR
* 287634915439517682...982743.4.3..298.9842.5.1..2.984.7871269354..4...829923845176
E4: 2                                    # 13 pairs
E5: 5,7,2                                # reduction candidate for 5,7
E5: 5,7                                  # 13 pairs
* PAIR F9: 3,5 BLK 8
F8: 3,5,1,7                              # reduction candidate for 3,5
F8: 3,5 => CTR
* 2876349154.9.1..8....98274..4.3.1.98.984.6..1..25984.787..69.54..4.538.99..84.17.
F8: 1,7                                  # 14 pairs
* PAIR F9: 3,5 ROW 9
B9: 3,5,2,6                              # reduction candidate for 3,5
B9: 3,5 => CTR
* 2876349154.9.1.28...3982746.4532.6983984.652161259843787126935452417.8699.684.172
B9: 2,6                                  # 12 pairs
C9: 3,5,6                                # reduction candidate for 3,5
C9: 3,5                                  # 15 pairs
* PAIR G7: 2,3 BLK 9
H8: 2,3,6                                # reduction candidate for 2,3
H8: 2,3                                  # 12 pairs
I9: 2,3,6                                # reduction candidate for 2,3
I9: 2,3                                  # 17 pairs
* PAIR G7: 2,3 COL G
G2: 2,3,6                                # reduction candidate for 2,3
G2: 2,3                                  # 17 pairs
G5: 2,3,5,6                              # reduction candidate for 2,3
G5: 2,3                                  # 14 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060815-absurd-base-pr-000.dot
* REASONING
* DIS # I2: 3,6 => CTR => I2: 2
* DIS # B9: 3,6 => CTR => B9: 2,5
* DIS # D8: 5,7 => CTR => D8: 1,2
* DIS # F4: 5,7 => CTR => F4: 1,6
* DIS # F5: 5,7 => CTR => F5: 6
* DIS # I2: 3,6 => CTR => I2: 2
* DIS # I9: 2 => CTR => I9: 3,6
* DIS # F4: 6,7 => CTR => F4: 1,5
* DIS # D8: 1,5 => CTR => D8: 2,7
* DIS # H5: 3,6 => CTR => H5: 2
* DIS # H8: 2 => CTR => H8: 3,6
* DIS # D8: 5,7 => CTR => D8: 1,2
* DIS # D8: 5,7 => CTR => D8: 1,2
* DIS # E4: 5,7 => CTR => E4: 2
* DIS # F8: 3,5 => CTR => F8: 1,7
* DIS # B9: 3,5 => CTR => B9: 2,6
* CNT  16 HDP CHAINS /  59 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (B2,C7,D2,D6,D7,E8,F2,F9,G7,H6,I3)
* 2876349154.9.1..8....98274..4.3...98.984....1..2.984.787..69.54..4...8.99..84.17.
* PAIR B2: 3,6 BLK 1
A3: 3,6,1,5                              # reduction candidate for 3,6
A3: 3,6                                  # 14 pairs
B3: 3,6,1,5                              # reduction candidate for 3,6
B3: 3,6                                  # 17 pairs
C3: 3,6,1,5                              # reduction candidate for 3,6
C3: 3,6                                  # 14 pairs
* PAIR B2: 3,6 ROW 2
G2: 3,6,2                                # reduction candidate for 3,6
G2: 3,6                                  # 13 pairs
I2: 3,6,2                                # reduction candidate for 3,6
I2: 3,6 => CTR
* 2876349154.9.1.28....98274..4.32..983984...21..2.98437871269354524.738699..845172
* RESTART
* PAIR B2: 3,6 COL B
B6: 3,6,1,5                              # reduction candidate for 3,6
B6: 3,6                                  # 17 pairs
B8: 3,6,1,5                              # reduction candidate for 3,6
B8: 3,6                                  # 17 pairs
* PAIR RESTART
* PAIR B2: 3,6 BLK 1
A3: 3,6,1,5                              # reduction candidate for 3,6
A3: 3,6                                  # 16 pairs
B3: 3,6,1,5                              # reduction candidate for 3,6
B3: 3,6                                  # 19 pairs
C3: 3,6,1,5                              # reduction candidate for 3,6
C3: 3,6                                  # 16 pairs
* PAIR B2: 3,6 COL B
B6: 3,6,1,5                              # reduction candidate for 3,6
B6: 3,6                                  # 17 pairs
B8: 3,6,1,5                              # reduction candidate for 3,6
B8: 3,6                                  # 17 pairs
* PAIR D2: 5,7 COL D
D8: 5,7,1,2                              # reduction candidate for 5,7
D8: 5,7 => CTR
* 287634915439.1.682...982743.4.3...98.984....1..21984.7871269354364..1829925843176
D8: 1,2 => SOLVED
* 287634915439715682651982743746321598598476321312598467873169254164257839925843176
* DURATION: 0:00:09.323019  START: 01:49:25.772482  END: 01:49:35.095501 2019-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060815-absurd-base-pr-001.dot
* REASONING
* DIS # I2: 3,6 => CTR => I2: 2
* DIS I2: 2 # D8: 5,7 => CTR => D8: 1,2
* PRF I2: 2 + D8: 1,2 => SOL
* STA I2: 2 + D8: 1,2
* CNT   3 HDP CHAINS /  13 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Aug&YEAR=2006, 20060815, absurd

Solution

position: 287634915439715682651982743746321598598476321312598467873169254164257839925843176 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:

* INC # A3: 3,6 => UNS
* INC # B3: 3,6 => UNS
* INC # C3: 3,6 => UNS
* INC # G2: 3,6 => UNS
* DIS # I2: 3,6 => CTR => I2: 2
* INC # I2: 2 => UNS
* INC # B6: 3,6 => UNS
* INC # B8: 3,6 => UNS
* DIS # B9: 3,6 => CTR => B9: 2,5
* INC # B9: 2,5 => UNS
* DIS # D8: 5,7 => CTR => D8: 1,2
* INC # D8: 1,2 => UNS
* DIS # F4: 5,7 => CTR => F4: 1,6
* INC # F4: 1,6 => UNS
* DIS # F5: 5,7 => CTR => F5: 6
* INC # F5: 6 => UNS
* INC # F8: 5,7 => UNS
* INC # G2: 3,6 => UNS
* DIS # I2: 3,6 => CTR => I2: 2
* INC # I2: 2 => UNS
* INC # A3: 3,6 => UNS
* INC # B3: 3,6 => UNS
* INC # C3: 3,6 => UNS
* INC # I9: 3,6 => UNS
* DIS # I9: 2 => CTR => I9: 3,6
* INC # F4: 1,5 => UNS
* DIS # F4: 6,7 => CTR => F4: 1,5
* INC # A6: 1,5 => UNS
* INC # B6: 1,5 => UNS
* DIS # D8: 1,5 => CTR => D8: 2,7
* INC # D8: 2,7 => UNS
* INC # G5: 3,6 => UNS
* DIS # H5: 3,6 => CTR => H5: 2
* INC # H5: 2 => UNS
* INC # A6: 3,6 => UNS
* INC # B6: 3,6 => UNS
* INC # H8: 3,6 => UNS
* DIS # H8: 2 => CTR => H8: 3,6
* INC # A8: 1,3 => UNS
* INC # B8: 1,3 => UNS
* INC # C3: 1,3 => UNS
* INC # C3: 5,6 => UNS
* INC # D8: 1,2 => UNS
* DIS # D8: 5,7 => CTR => D8: 1,2
* DIS # D8: 5,7 => CTR => D8: 1,2
* INC # D8: 1,2 => UNS
* INC # F8: 5,7 => UNS
* DIS # E4: 5,7 => CTR => E4: 2
* INC # E4: 2 => UNS
* INC # E5: 5,7 => UNS
* DIS # F8: 3,5 => CTR => F8: 1,7
* INC # F8: 1,7 => UNS
* DIS # B9: 3,5 => CTR => B9: 2,6
* INC # B9: 2,6 => UNS
* INC # C9: 3,5 => UNS
* INC # H8: 2,3 => UNS
* INC # I9: 2,3 => UNS
* INC # G2: 2,3 => UNS
* INC # G5: 2,3 => UNS
* CNT  59 HDP CHAINS /  59 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # A3: 3,6 => UNS
* INC # B3: 3,6 => UNS
* INC # C3: 3,6 => UNS
* INC # G2: 3,6 => UNS
* DIS # I2: 3,6 => CTR => I2: 2
* INC I2: 2 # B6: 3,6 => UNS
* INC I2: 2 # B8: 3,6 => UNS
* INC I2: 2 # A3: 3,6 => UNS
* INC I2: 2 # B3: 3,6 => UNS
* INC I2: 2 # C3: 3,6 => UNS
* INC I2: 2 # B6: 3,6 => UNS
* INC I2: 2 # B8: 3,6 => UNS
* DIS I2: 2 # D8: 5,7 => CTR => D8: 1,2
* PRF I2: 2 + D8: 1,2 => SOL
* STA I2: 2 + D8: 1,2
* CNT  14 HDP CHAINS /  13 HYP OPENED