Analysis of zz-www.sudokuoftheday.co.uk-20060805-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: ......93.5.7.......1.4....7........96...7.1...21.....8.59.62.14..4.83.....69..5.. initial

Autosolve

position: .....793.5.7...4...1.4....7........96...7.1...21.....8359762814174583.9.2869..573 autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # A4: 7 => CTR => A4: 4,8
* DIS # I1: 2,6 => CTR => I1: 1,5
* DIS # B5: 3,4 => CTR => B5: 9
* DIS # E4: 3,4 => CTR => E4: 1,2,5
* DIS # H4: 2,5 => CTR => H4: 4,6
* DIS # I1: 2,6 => CTR => I1: 1,5
* CNT   6 HDP CHAINS /  35 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 # A4: 7 => CTR => A4: 4,8
* DIS A4: 4,8 # C3: 3 => CTR => C3: 2,8
* PRF A4: 4,8 + C3: 2,8 # H3: 2,8 => SOL
* STA A4: 4,8 + C3: 2,8 + H3: 2,8
* CNT   3 HDP CHAINS /   7 HYP OPENED

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

Details

Positions

......93.5.7.......1.4....7........96...7.1...21.....8.59.62.14..4.83.....69..5.. initial
.....793.5.7...4...1.4....7........96...7.1...21.....8359762814174583.9.2869..573 autosolve
468127935537896421912435687843251769695378142721649358359762814174583296286914573 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (15)
A1: 4,8
B1: 4,6
C1: 2,8
A3: 8,9
H2: 2,8
G3: 2,6
B4: 3,4
D6: 3,6
G4: 3,7
I5: 2,5
G6: 3,7
E9: 1,4
F9: 1,4
G8: 2,6
I8: 2,6

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
I1,I2: 1.. / I1 = 1  => 17 pairs (_) / I2 = 1  => 15 pairs (_)
E9,F9: 1.. / E9 = 1  => 14 pairs (_) / F9 = 1  => 13 pairs (_)
C1,C3: 2.. / C1 = 2  => 16 pairs (_) / C3 = 2  => 14 pairs (_)
G8,I8: 2.. / G8 = 2  => 13 pairs (_) / I8 = 2  => 17 pairs (_)
G3,G8: 2.. / G3 = 2  => 17 pairs (_) / G8 = 2  => 13 pairs (_)
B2,C3: 3.. / B2 = 3  => 14 pairs (_) / C3 = 3  => 19 pairs (_)
G4,G6: 3.. / G4 = 3  =>  0 pairs (X) / G6 = 3  => 15 pairs (_)
C3,E3: 3.. / C3 = 3  => 19 pairs (_) / E3 = 3  => 14 pairs (_)
A1,B1: 4.. / A1 = 4  => 16 pairs (_) / B1 = 4  =>  0 pairs (X)
E9,F9: 4.. / E9 = 4  => 13 pairs (_) / F9 = 4  => 14 pairs (_)
I1,H3: 5.. / I1 = 5  => 15 pairs (_) / H3 = 5  => 16 pairs (_)
C4,C5: 5.. / C4 = 5  => 16 pairs (_) / C5 = 5  => 20 pairs (_)
E1,I1: 5.. / E1 = 5  => 16 pairs (_) / I1 = 5  => 15 pairs (_)
I1,I5: 5.. / I1 = 5  => 15 pairs (_) / I5 = 5  => 16 pairs (_)
B1,B2: 6.. / B1 = 6  => 16 pairs (_) / B2 = 6  =>  0 pairs (X)
H4,H6: 6.. / H4 = 6  => 17 pairs (_) / H6 = 6  =>  0 pairs (X)
G8,I8: 6.. / G8 = 6  => 17 pairs (_) / I8 = 6  => 13 pairs (_)
F3,G3: 6.. / F3 = 6  => 17 pairs (_) / G3 = 6  => 13 pairs (_)
G3,G8: 6.. / G3 = 6  => 13 pairs (_) / G8 = 6  => 17 pairs (_)
A4,A6: 7.. / A4 = 7  =>  0 pairs (X) / A6 = 7  => 15 pairs (_)
G4,G6: 7.. / G4 = 7  => 15 pairs (_) / G6 = 7  =>  0 pairs (X)
A4,G4: 7.. / A4 = 7  =>  0 pairs (X) / G4 = 7  => 15 pairs (_)
A6,G6: 7.. / A6 = 7  => 15 pairs (_) / G6 = 7  =>  0 pairs (X)
H2,H3: 8.. / H2 = 8  => 15 pairs (_) / H3 = 8  =>  0 pairs (*)
B2,A3: 9.. / B2 = 9  =>  0 pairs (X) / A3 = 9  => 16 pairs (_)
B5,A6: 9.. / B5 = 9  => 16 pairs (_) / A6 = 9  =>  0 pairs (X)
B5,F5: 9.. / B5 = 9  => 16 pairs (_) / F5 = 9  =>  0 pairs (X)
A3,A6: 9.. / A3 = 9  => 16 pairs (_) / A6 = 9  =>  0 pairs (X)
B2,B5: 9.. / B2 = 9  =>  0 pairs (X) / B5 = 9  => 16 pairs (_)
* DURATION: 0:00:35.350194  START: 01:34:52.769054  END: 01:35:28.119248 2019-05-01
* CP COUNT: (29)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A1,A3,B1,B4,C1,D6,E9,F9,G3,G4,G6,G8,H2,I5,I8)
* .....793.5.7...4...1.4....7........96...7.1...21.....8359762814174583.9.2869..573
* PAIR A1: 4,8 COL A
A4: 4,8,7                                # reduction candidate for 4,8
A4: 7 => CTR
* 462857931597.2.4868134962577456183296382791459213..768359762814174583.9.2869..573
A4: 4,8                                  # 15 pairs
* PAIR C1: 2,8 BLK 1
C3: 2,8,3                                # reduction candidate for 2,8
C3: 3                                    # 19 pairs
C3: 2,8                                  # 14 pairs
* PAIR C1: 2,8 ROW 1
D1: 2,8,1,6                              # reduction candidate for 2,8
D1: 2,8                                  # 19 pairs
D1: 1,6                                  # 18 pairs
* PAIR A3: 8,9 ROW 3
F3: 8,9,5,6                              # reduction candidate for 8,9
F3: 5,6                                  # 16 pairs
F3: 8,9                                  # 15 pairs
* PAIR H2: 2,8 BLK 3
H3: 2,8,5                                # reduction candidate for 2,8
H3: 5                                    # 16 pairs
H3: 2,8                                  # 15 pairs
* PAIR H2: 2,8 ROW 2
D2: 2,8,1,3,6                            # reduction candidate for 2,8
D2: 2,8                                  # 17 pairs
D2: 1,3,6                                # 15 pairs
* PAIR G3: 2,6 BLK 3
I1: 2,6,1,5                              # reduction candidate for 2,6
I1: 2,6 => CTR
* 468157932537.2948191243865784521...9693874125.21.95..8359762814174583296286941573
I1: 1,5                                  # 16 pairs
I2: 2,6,1                                # reduction candidate for 2,6
I2: 2,6                                  # 17 pairs
* PAIR B4: 3,4 BLK 4
B5: 3,4,9                                # reduction candidate for 3,4
B5: 3,4 => CTR
* 462857931597.2.4868134962577456183296382791459213..768359762814174583.9.2869..573
B5: 9                                    # 16 pairs
* PAIR B4: 3,4 ROW 4
E4: 3,4,1,2,5                            # reduction candidate for 3,4
E4: 3,4 => CTR
* 46...793.537...4..91.43...7845...7.96.3.7.1..721...3.8359762814174583.9.2869..573
E4: 1,2,5                                # 15 pairs
* PAIR D6: 3,6 BLK 5
D4: 3,6,1,2,8                            # reduction candidate for 3,6
D4: 3,6                                  # 20 pairs
D4: 1,2,8                                # 15 pairs
* PAIR D6: 3,6 COL D
D2: 3,6,1,2,8                            # reduction candidate for 3,6
D2: 3,6                                  # 19 pairs
D2: 1,2,8                                # 15 pairs
* PAIR I5: 2,5 BLK 6
H4: 2,5,4,6                              # reduction candidate for 2,5
H4: 2,5 => CTR
* 4628.793.59723.4..81349...774....3.963..7914.9213..768359762814174583.9.2869..573
H4: 4,6                                  # 17 pairs
H5: 2,5,4                                # reduction candidate for 2,5
H5: 2,5                                  # 22 pairs
* PAIR I5: 2,5 COL I
I1: 2,5,1,6                              # reduction candidate for 2,5
I1: 1,6                                  # 17 pairs
I1: 2,5                                  # 13 pairs
* PAIR E9: 1,4 COL E
E4: 1,4,2,3,5                            # reduction candidate for 1,4
E4: 1,4                                  # 17 pairs
E4: 2,3,5                                # 15 pairs
* PAIR F9: 1,4 COL F
F4: 1,4,5,6,8                            # reduction candidate for 1,4
F4: 1,4                                  # 16 pairs
F4: 5,6,8                                # 15 pairs
* PAIR I8: 2,6 COL I
I1: 2,6,1,5                              # reduction candidate for 2,6
I1: 2,6 => CTR
* 468157932537.2948191243865784521...9693874125.21.95..8359762814174583296286941573
I1: 1,5                                  # 16 pairs
I2: 2,6,1                                # reduction candidate for 2,6
I2: 2,6                                  # 17 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060805-absurd-base-pr-000.dot
* REASONING
* DIS # A4: 7 => CTR => A4: 4,8
* DIS # I1: 2,6 => CTR => I1: 1,5
* DIS # B5: 3,4 => CTR => B5: 9
* DIS # E4: 3,4 => CTR => E4: 1,2,5
* DIS # H4: 2,5 => CTR => H4: 4,6
* DIS # I1: 2,6 => CTR => I1: 1,5
* CNT   6 HDP CHAINS /  35 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A1,A3,B1,B4,C1,D6,E9,F9,G3,G4,G6,G8,H2,I5,I8)
* .....793.5.7...4...1.4....7........96...7.1...21.....8359762814174583.9.2869..573
* PAIR A1: 4,8 COL A
A4: 4,8,7                                # reduction candidate for 4,8
A4: 7 => CTR
* 462857931597.2.4868134962577456183296382791459213..768359762814174583.9.2869..573
* PAIR RESTART
* PAIR C1: 2,8 BLK 1
C3: 2,8,3                                # reduction candidate for 2,8
C3: 3 => CTR
* 842157936567.394.191342...7.3....76969.37.1..7216..3.8359762814174583.9.2869..573
* PAIR C1: 2,8 ROW 1
D1: 2,8,1                                # reduction candidate for 2,8
D1: 2,8                                  # 17 pairs
D1: 1                                    # 16 pairs
* PAIR H2: 2,8 BLK 3
H3: 2,8,5                                # reduction candidate for 2,8
H3: 2,8 => SOLVED
* 468127935537896421912435687843251769695378142721649358359762814174583296286914573
* DURATION: 0:00:06.419545  START: 01:35:50.296572  END: 01:35:56.716117 2019-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060805-absurd-base-pr-001.dot
* REASONING
* DIS # A4: 7 => CTR => A4: 4,8
* DIS A4: 4,8 # C3: 3 => CTR => C3: 2,8
* PRF A4: 4,8 + C3: 2,8 # H3: 2,8 => SOL
* STA A4: 4,8 + C3: 2,8 + H3: 2,8
* CNT   3 HDP CHAINS /   7 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Aug&YEAR=2006, 20060805, absurd

Solution

position: 468127935537896421912435687843251769695378142721649358359762814174583296286914573 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 # A4: 4,8 => UNS
* DIS # A4: 7 => CTR => A4: 4,8
* INC # C3: 2,8 => UNS
* INC # C3: 3 => UNS
* INC # D1: 2,8 => UNS
* INC # D1: 1,6 => UNS
* INC # F3: 8,9 => UNS
* INC # F3: 5,6 => UNS
* INC # H3: 2,8 => UNS
* INC # H3: 5 => UNS
* INC # D2: 2,8 => UNS
* INC # D2: 1,3,6 => UNS
* DIS # I1: 2,6 => CTR => I1: 1,5
* INC # I1: 1,5 => UNS
* INC # I2: 2,6 => UNS
* DIS # B5: 3,4 => CTR => B5: 9
* INC # B5: 9 => UNS
* DIS # E4: 3,4 => CTR => E4: 1,2,5
* INC # E4: 1,2,5 => UNS
* INC # D4: 3,6 => UNS
* INC # D4: 1,2,8 => UNS
* INC # D2: 3,6 => UNS
* INC # D2: 1,2,8 => UNS
* DIS # H4: 2,5 => CTR => H4: 4,6
* INC # H4: 4,6 => UNS
* INC # H5: 2,5 => UNS
* INC # I1: 2,5 => UNS
* INC # I1: 1,6 => UNS
* INC # E4: 1,4 => UNS
* INC # E4: 2,3,5 => UNS
* INC # F4: 1,4 => UNS
* INC # F4: 5,6,8 => UNS
* DIS # I1: 2,6 => CTR => I1: 1,5
* INC # I1: 1,5 => UNS
* INC # I2: 2,6 => UNS
* CNT  35 HDP CHAINS /  35 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # A4: 4,8 => UNS
* DIS # A4: 7 => CTR => A4: 4,8
* INC A4: 4,8 # C3: 2,8 => UNS
* DIS A4: 4,8 # C3: 3 => CTR => C3: 2,8
* INC A4: 4,8 + C3: 2,8 # D1: 2,8 => UNS
* INC A4: 4,8 + C3: 2,8 # D1: 1 => UNS
* PRF A4: 4,8 + C3: 2,8 # H3: 2,8 => SOL
* STA A4: 4,8 + C3: 2,8 + H3: 2,8
* CNT   7 HDP CHAINS /   7 HYP OPENED