Analysis of zz-www.sudokuoftheday.co.uk-20060617-absurd-base.sdk

Contents

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

level: medium

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

position: ....5..84.65..4......1..3..........7.3.6.725..2....9..3....8..2..8.1.....1.2...7. initial

Autosolve

position: 1.3.52684.65..4721..21.6395....2...7.316.7258.2....9..3....8..22.8.1.....1.2..87. autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # B7: 7,9 => CTR => B7: 4,5
* PRF # B7: 4,5 => SOL
* PRF # B8: 7,9 => SOL
* DIS # B8: 4,5 => CTR => B8: 7,9
* DIS # A4: 8,9 => CTR => A4: 4,5,6
* PRF # D7: 7,9 => SOL
* DIS # D7: 4,5 => CTR => D7: 7,9
* DIS # D8: 7,9 => CTR => D8: 3,4,5
* PRF # D8: 3,4,5 => SOL
* DIS # B3: 7,8 => CTR => B3: 4
* DIS # A4: 4,9 => CTR => A4: 5,6,8
* DIS # B4: 4,9 => CTR => B4: 5,8
* PRF # A9: 4,9 => SOL
* DIS # E7: 4,9 => CTR => E7: 6,7
* DIS # E9: 4,9 => CTR => E9: 3,6
* DIS # B8: 4,5 => CTR => B8: 7,9
* PRF # B8: 7,9 => SOL
* PRF # D8: 4,5 => SOL
* DIS # E9: 3,9 => CTR => E9: 4,6
* DIS # F9: 3,9 => CTR => F9: 5
* CNT  20 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:

* DIS # B7: 7,9 => CTR => B7: 4,5
* PRF B7: 4,5 => SOL
* STA B7: 4,5
* CNT   2 HDP CHAINS /   1 HYP OPENED

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

Details

Positions

....5..84.65..4......1..3..........7.3.6.725..2....9..3....8..2..8.1.....1.2...7. initial
1.3.52684.65..4721..21.6395....2...7.316.7258.2....9..3....8..22.8.1.....1.2..87. autosolve
193752684865394721742186395684529137931647258527831946356978412278413569419265873 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (12)
B1: 7,9
A2: 8,9
D1: 7,9
E3: 7,8
A5: 4,9
E5: 4,9
G4: 1,4
I6: 3,6
H7: 1,4
G8: 4,5
H8: 3,6
I9: 3,9

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
F4,F6: 1.. / F4 = 1  => 18 pairs (_) / F6 = 1  => 12 pairs (_)
G7,H7: 1.. / G7 = 1  => 13 pairs (_) / H7 = 1  => 11 pairs (_)
F6,H6: 1.. / F6 = 1  => 12 pairs (_) / H6 = 1  => 18 pairs (_)
G4,G7: 1.. / G4 = 1  => 11 pairs (_) / G7 = 1  => 13 pairs (_)
D2,E2: 3.. / D2 = 3  => 14 pairs (_) / E2 = 3  => 14 pairs (_)
A3,B3: 4.. / A3 = 4  =>  0 pairs (X) / B3 = 4  => 19 pairs (_)
A5,E5: 4.. / A5 = 4  =>  0 pairs (X) / E5 = 4  =>  0 pairs (_)
G7,G8: 5.. / G7 = 5  =>  9 pairs (_) / G8 = 5  => 15 pairs (_)
A9,F9: 5.. / A9 = 5  =>  0 pairs (X) / F9 = 5  => 19 pairs (_)
E7,E9: 6.. / E7 = 6  =>  0 pairs (X) / E9 = 6  =>  0 pairs (_)
H8,I8: 6.. / H8 = 6  => 12 pairs (_) / I8 = 6  => 14 pairs (_)
C7,E7: 6.. / C7 = 6  =>  0 pairs (*) / E7 = 6  =>  0 pairs (X)
I6,I8: 6.. / I6 = 6  => 12 pairs (_) / I8 = 6  => 14 pairs (_)
D1,E3: 7.. / D1 = 7  =>  0 pairs (*) / E3 = 7  =>  0 pairs (X)
A6,C6: 7.. / A6 = 7  =>  0 pairs (X) / C6 = 7  =>  0 pairs (_)
B1,D1: 7.. / B1 = 7  =>  0 pairs (X) / D1 = 7  =>  0 pairs (_)
B8,D8: 7.. / B8 = 7  =>  0 pairs (*) / D8 = 7  =>  0 pairs (X)
A3,A6: 7.. / A3 = 7  =>  0 pairs (*) / A6 = 7  =>  0 pairs (X)
C6,C7: 7.. / C6 = 7  =>  0 pairs (*) / C7 = 7  =>  0 pairs (X)
E3,E7: 7.. / E3 = 7  =>  0 pairs (X) / E7 = 7  =>  0 pairs (_)
B3,B4: 8.. / B3 = 8  =>  0 pairs (X) / B4 = 8  => 19 pairs (_)
B1,A2: 9.. / B1 = 9  =>  0 pairs (*) / A2 = 9  =>  0 pairs (X)
I8,I9: 9.. / I8 = 9  => 12 pairs (_) / I9 = 9  => 15 pairs (_)
B1,D1: 9.. / B1 = 9  =>  0 pairs (*) / D1 = 9  =>  0 pairs (X)
A5,E5: 9.. / A5 = 9  =>  0 pairs (*) / E5 = 9  =>  0 pairs (X)
* DURATION: 0:00:26.664680  START: 23:54:42.087337  END: 23:55:08.752017 2019-04-30
* CP COUNT: (25)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A2,A5,B1,D1,E3,E5,G4,G8,H7,H8,I6,I9)
* 1.3.52684.65..4721..21.6395....2...7.316.7258.2....9..3....8..22.8.1.....1.2..87.
* PAIR B1: 7,9 COL B
B7: 7,9,4,5                              # reduction candidate for 7,9
B7: 7,9 => CTR
* 17395268496538472184217639558942...7431697258726...9.3397.68..22.871..36614235879
B7: 4,5 => SOLVED
* 193752684865394721742186395684529137931647258527831946356978412278413569419265873
B8: 7,9,4,5                              # reduction candidate for 7,9
B8: 7,9 => SOLVED
* 193752684865394721742186395684529137931647258527831946356978412278413569419265873
B8: 4,5 => CTR
* 17395268496538472184217639558942...7431697258726...9.33.7.68..22.871..36614235879
* PAIR A2: 8,9 ROW 2
D2: 8,9,3                                # reduction candidate for 8,9
D2: 8,9                                  # 14 pairs
E2: 8,9,3                                # reduction candidate for 8,9
E2: 8,9                                  # 14 pairs
* PAIR A2: 8,9 COL A
A4: 8,9,4,5,6                            # reduction candidate for 8,9
A4: 8,9 => CTR
* 1.3.52684.65..4721742186395.8..2...74316972585278..9..3...78..2278.1....61.2.587.
A4: 4,5,6                                # 12 pairs
* PAIR D1: 7,9 COL D
D7: 7,9,4,5                              # reduction candidate for 7,9
D7: 7,9 => SOLVED
* 193752684865394721742186395684529137931647258527831946356978412278413569419265873
D7: 4,5 => CTR
* 17395268496538472184217639558942...7431697258726...9.3397.68..22.871..36614235879
D8: 7,9,3,4,5                            # reduction candidate for 7,9
D8: 7,9 => CTR
* 17395268496538472184217639558942...7431697258726...9.3397.68..22.871..36614235879
D8: 3,4,5 => SOLVED
* 193752684865394721742186395684529137931647258527831946356978412278413569419265873
* PAIR E3: 7,8 ROW 3
A3: 7,8,4                                # reduction candidate for 7,8
A3: 7,8                                  # 19 pairs
B3: 7,8,4                                # reduction candidate for 7,8
B3: 7,8 => CTR
* 1.3.52684.65..47214.21.6395....2...793164725872....9..3.7.68..22.871.....1.2..87.
B3: 4                                    # 19 pairs
* PAIR A5: 4,9 BLK 4
A4: 4,9,5,6,8                            # reduction candidate for 4,9
A4: 4,9 => CTR
* 193752684865..4721742186395....2...7.316.7258.2....9..3....8..22.8.1.....1.2..87.
A4: 5,6,8                                # 12 pairs
B4: 4,9,5,8                              # reduction candidate for 4,9
B4: 4,9 => CTR
* 1.3.52684.65..4721.82176395....2...7.316.725872....9..3.7.68..22.871.....1.2..87.
B4: 5,8                                  # 13 pairs
C4: 4,9,6                                # reduction candidate for 4,9
C4: 4,9                                  # 15 pairs
* PAIR A5: 4,9 COL A
A9: 4,9,5,6                              # reduction candidate for 4,9
A9: 4,9 => SOLVED
* 193752684865394721742186395684529137931647258527831946356978412278413569419265873
A9: 5,6                                  # 13 pairs
* PAIR E5: 4,9 BLK 5
D4: 4,9,3,5,8                            # reduction candidate for 4,9
D4: 4,9                                  # 15 pairs
D4: 3,5,8                                # 12 pairs
* PAIR E5: 4,9 COL E
E7: 4,9,6,7                              # reduction candidate for 4,9
E7: 4,9 => CTR
* 1.3.52684.65..4721..2176395....2...7.316.725872....9..3....8..22.8.1.....1.2..87.
E7: 6,7                                  # 13 pairs
E9: 4,9,3,6                              # reduction candidate for 4,9
E9: 4,9 => CTR
* 173952684965..4721..2176395....2...7431697258726...9.3397.68..22.871..366142..87.
E9: 3,6                                  # 20 pairs
* PAIR G4: 1,4 BLK 6
H4: 1,4,3,6                              # reduction candidate for 1,4
H4: 1,4                                  # 17 pairs
H6: 1,4,3,6                              # reduction candidate for 1,4
H6: 1,4                                  # 14 pairs
* PAIR G4: 1,4 COL G
G7: 1,4,5                                # reduction candidate for 1,4
G7: 1,4                                  # 15 pairs
G7: 5                                    #  9 pairs
* PAIR I6: 3,6 BLK 6
H4: 3,6,1,4                              # reduction candidate for 3,6
H4: 3,6                                  # 14 pairs
H6: 3,6,1,4                              # reduction candidate for 3,6
H6: 3,6                                  # 17 pairs
* PAIR I6: 3,6 COL I
I8: 3,6,9                                # reduction candidate for 3,6
I8: 3,6                                  # 15 pairs
I8: 9                                    # 12 pairs
* PAIR H7: 1,4 BLK 9
G7: 1,4,5                                # reduction candidate for 1,4
G7: 1,4                                  # 15 pairs
G7: 5                                    #  9 pairs
* PAIR H7: 1,4 COL H
H4: 1,4,3,6                              # reduction candidate for 1,4
H4: 1,4                                  # 17 pairs
H6: 1,4,3,6                              # reduction candidate for 1,4
H6: 1,4                                  # 14 pairs
* PAIR G8: 4,5 BLK 9
G7: 4,5,1                                # reduction candidate for 4,5
G7: 1                                    # 13 pairs
G7: 4,5                                  # 11 pairs
* PAIR G8: 4,5 ROW 8
B8: 4,5,7,9                              # reduction candidate for 4,5
B8: 4,5 => CTR
* 17395268496538472184217639558942...7431697258726...9.33.7.68..22.871..36614235879
B8: 7,9 => SOLVED
* 193752684865394721742186395684529137931647258527831946356978412278413569419265873
D8: 4,5,3,7,9                            # reduction candidate for 4,5
D8: 4,5 => SOLVED
* 193752684865394721742186395684529137931647258527831946356978412278413569419265873
D8: 3,7,9                                # 12 pairs
* PAIR H8: 3,6 BLK 9
I8: 3,6,9                                # reduction candidate for 3,6
I8: 3,6                                  # 15 pairs
I8: 9                                    # 12 pairs
* PAIR H8: 3,6 COL H
H4: 3,6,1,4                              # reduction candidate for 3,6
H4: 3,6                                  # 14 pairs
H6: 3,6,1,4                              # reduction candidate for 3,6
H6: 3,6                                  # 17 pairs
* PAIR I9: 3,9 BLK 9
I8: 3,9,6                                # reduction candidate for 3,9
I8: 6                                    # 14 pairs
I8: 3,9                                  # 12 pairs
* PAIR I9: 3,9 ROW 9
E9: 3,9,4,6                              # reduction candidate for 3,9
E9: 3,9 => CTR
* 173952684965..4721..2176395....2...7431697258726.4.9.33974685122.871.....1.2..87.
E9: 4,6                                  # 13 pairs
F9: 3,9,5                                # reduction candidate for 3,9
F9: 3,9 => CTR
* 1.3.52684.65..4721.82176395.5..2...7.316.725872....9..3.7.68..22.871....51624.87.
F9: 5                                    # 19 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060617-absurd-base-pr-000.dot
* REASONING
* DIS # B7: 7,9 => CTR => B7: 4,5
* PRF # B7: 4,5 => SOL
* PRF # B8: 7,9 => SOL
* DIS # B8: 4,5 => CTR => B8: 7,9
* DIS # A4: 8,9 => CTR => A4: 4,5,6
* PRF # D7: 7,9 => SOL
* DIS # D7: 4,5 => CTR => D7: 7,9
* DIS # D8: 7,9 => CTR => D8: 3,4,5
* PRF # D8: 3,4,5 => SOL
* DIS # B3: 7,8 => CTR => B3: 4
* DIS # A4: 4,9 => CTR => A4: 5,6,8
* DIS # B4: 4,9 => CTR => B4: 5,8
* PRF # A9: 4,9 => SOL
* DIS # E7: 4,9 => CTR => E7: 6,7
* DIS # E9: 4,9 => CTR => E9: 3,6
* DIS # B8: 4,5 => CTR => B8: 7,9
* PRF # B8: 7,9 => SOL
* PRF # D8: 4,5 => SOL
* DIS # E9: 3,9 => CTR => E9: 4,6
* DIS # F9: 3,9 => CTR => F9: 5
* CNT  20 HDP CHAINS /  56 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A2,A5,B1,D1,E3,E5,G4,G8,H7,H8,I6,I9)
* 1.3.52684.65..4721..21.6395....2...7.316.7258.2....9..3....8..22.8.1.....1.2..87.
* PAIR B1: 7,9 COL B
B7: 7,9,4,5                              # reduction candidate for 7,9
B7: 7,9 => CTR
* 17395268496538472184217639558942...7431697258726...9.3397.68..22.871..36614235879
B7: 4,5 => SOLVED
* 193752684865394721742186395684529137931647258527831946356978412278413569419265873
* DURATION: 0:00:01.411368  START: 23:55:42.148249  END: 23:55:43.559617 2019-04-30
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060617-absurd-base-pr-001.dot
* REASONING
* DIS # B7: 7,9 => CTR => B7: 4,5
* PRF B7: 4,5 => SOL
* STA B7: 4,5
* CNT   2 HDP CHAINS /   1 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Jun&YEAR=2006, 20060617, absurd

Solution

position: 193752684865394721742186395684529137931647258527831946356978412278413569419265873 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 # B7: 7,9 => CTR => B7: 4,5
* PRF # B7: 4,5 => SOL
* PRF # B8: 7,9 => SOL
* DIS # B8: 4,5 => CTR => B8: 7,9
* INC # D2: 8,9 => UNS
* INC # E2: 8,9 => UNS
* DIS # A4: 8,9 => CTR => A4: 4,5,6
* INC # A4: 4,5,6 => UNS
* PRF # D7: 7,9 => SOL
* DIS # D7: 4,5 => CTR => D7: 7,9
* DIS # D8: 7,9 => CTR => D8: 3,4,5
* PRF # D8: 3,4,5 => SOL
* INC # A3: 7,8 => UNS
* DIS # B3: 7,8 => CTR => B3: 4
* INC # B3: 4 => UNS
* DIS # A4: 4,9 => CTR => A4: 5,6,8
* INC # A4: 5,6,8 => UNS
* DIS # B4: 4,9 => CTR => B4: 5,8
* INC # B4: 5,8 => UNS
* INC # C4: 4,9 => UNS
* PRF # A9: 4,9 => SOL
* INC # A9: 5,6 => UNS
* INC # D4: 4,9 => UNS
* INC # D4: 3,5,8 => UNS
* DIS # E7: 4,9 => CTR => E7: 6,7
* INC # E7: 6,7 => UNS
* DIS # E9: 4,9 => CTR => E9: 3,6
* INC # E9: 3,6 => UNS
* INC # H4: 1,4 => UNS
* INC # H6: 1,4 => UNS
* INC # G7: 1,4 => UNS
* INC # G7: 5 => UNS
* INC # H4: 3,6 => UNS
* INC # H6: 3,6 => UNS
* INC # I8: 3,6 => UNS
* INC # I8: 9 => UNS
* INC # G7: 1,4 => UNS
* INC # G7: 5 => UNS
* INC # H4: 1,4 => UNS
* INC # H6: 1,4 => UNS
* INC # G7: 4,5 => UNS
* INC # G7: 1 => UNS
* DIS # B8: 4,5 => CTR => B8: 7,9
* PRF # B8: 7,9 => SOL
* PRF # D8: 4,5 => SOL
* INC # D8: 3,7,9 => UNS
* INC # I8: 3,6 => UNS
* INC # I8: 9 => UNS
* INC # H4: 3,6 => UNS
* INC # H6: 3,6 => UNS
* INC # I8: 3,9 => UNS
* INC # I8: 6 => UNS
* DIS # E9: 3,9 => CTR => E9: 4,6
* INC # E9: 4,6 => UNS
* DIS # F9: 3,9 => CTR => F9: 5
* INC # F9: 5 => UNS
* CNT  56 HDP CHAINS /  56 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* DIS # B7: 7,9 => CTR => B7: 4,5
* PRF B7: 4,5 => SOL
* STA B7: 4,5
* CNT   2 HDP CHAINS /   1 HYP OPENED