Analysis of zz-www.sudokuoftheday.co.uk-20060728-absurd-base.sdk

Contents

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

level: medium

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

position: ........2..5167.......528....8..3...9.....5.....695...1.9.2.4.7..6.7.1...37..1.68 initial

Autosolve

position: ....3..52..5167.......528....8.13...9...845.....695.8.1.9.26437..637.1.5.37.41.68 autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* PRF # C6: 1,4 => SOL
* DIS # A8: 2,8 => CTR => A8: 4
* DIS # B8: 4 => CTR => B8: 2,8
* DIS # A3: 3,4 => CTR => A3: 6,7
* DIS # C6: 3,4 => CTR => C6: 1,2
* DIS # D1: 8 => CTR => D1: 4,9
* DIS # B3: 6,7 => CTR => B3: 4,9
* DIS # B1: 6,7 => CTR => B1: 1,4,9
* DIS # G4: 2,9 => CTR => G4: 6,7
* DIS # I2: 3 => CTR => I2: 4,9
* DIS # H4: 2,7 => CTR => H4: 4,9
* DIS # H5: 2 => CTR => H5: 1,7
* DIS # I5: 1,6 => CTR => I5: 3
* PRF # G4: 2,7 => SOL
* DIS # H4: 2,7 => CTR => H4: 4,9
* DIS # H5: 2,7 => CTR => H5: 1
* DIS # G4: 2,9 => CTR => G4: 6,7
* CNT  17 HDP CHAINS /  43 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 # C6: 1,4 => SOL
* STA C6: 1,4
* CNT   1 HDP CHAINS /   3 HYP OPENED

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

Details

Positions

........2..5167.......528....8..3...9.....5.....695...1.9.2.4.7..6.7.1...37..1.68 initial
....3..52..5167.......528....8.13...9...845.....695.8.1.9.26437..637.1.5.37.41.68 autosolve
714938652825167349693452871548213796962784513371695284159826437486379125237541968 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (20)
C1: 1,4
A2: 2,8
B2: 2,8
C3: 3,4
F1: 8,9
D3: 4,9
G1: 6,7
G2: 3,9
H2: 4,9
H3: 1,7
I3: 1,6
D4: 2,7
D5: 2,7
B7: 5,8
A9: 2,5
D7: 5,8
F8: 8,9
D9: 5,9
H8: 2,9
G9: 2,9

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
B1,C1: 1.. / B1 = 1  => 26 pairs (_) / C1 = 1  => 20 pairs (_)
H3,I3: 1.. / H3 = 1  =>  0 pairs (X) / I3 = 1  => 22 pairs (_)
H3,H5: 1.. / H3 = 1  =>  0 pairs (X) / H5 = 1  => 22 pairs (_)
A2,B2: 2.. / A2 = 2  =>  0 pairs (X) / B2 = 2  => 20 pairs (_)
C5,C6: 2.. / C5 = 2  =>  0 pairs (*) / C6 = 2  =>  0 pairs (X)
D4,D5: 2.. / D4 = 2  => 20 pairs (_) / D5 = 2  => 23 pairs (_)
H8,G9: 2.. / H8 = 2  => 16 pairs (_) / G9 = 2  =>  0 pairs (X)
C6,G6: 2.. / C6 = 2  => 24 pairs (_) / G6 = 2  =>  0 pairs (*)
A9,G9: 2.. / A9 = 2  => 16 pairs (_) / G9 = 2  =>  0 pairs (X)
B2,B8: 2.. / B2 = 2  => 20 pairs (_) / B8 = 2  =>  0 pairs (X)
A3,C3: 3.. / A3 = 3  =>  0 pairs (X) / C3 = 3  => 22 pairs (_)
G2,I2: 3.. / G2 = 3  => 21 pairs (_) / I2 = 3  =>  0 pairs (X)
C5,I5: 3.. / C5 = 3  =>  0 pairs (X) / I5 = 3  => 23 pairs (_)
A3,A6: 3.. / A3 = 3  =>  0 pairs (X) / A6 = 3  => 22 pairs (_)
G2,G6: 3.. / G2 = 3  => 21 pairs (_) / G6 = 3  =>  0 pairs (X)
D1,D3: 4.. / D1 = 4  => 15 pairs (_) / D3 = 4  => 23 pairs (_)
H2,I2: 4.. / H2 = 4  => 20 pairs (_) / I2 = 4  => 15 pairs (_)
A8,B8: 4.. / A8 = 4  => 16 pairs (_) / B8 = 4  =>  0 pairs (X)
H2,H4: 4.. / H2 = 4  => 20 pairs (_) / H4 = 4  => 15 pairs (_)
A4,B4: 5.. / A4 = 5  => 16 pairs (_) / B4 = 5  =>  0 pairs (X)
B7,A9: 5.. / B7 = 5  => 16 pairs (_) / A9 = 5  =>  0 pairs (X)
D7,D9: 5.. / D7 = 5  =>  0 pairs (X) / D9 = 5  => 16 pairs (_)
B7,D7: 5.. / B7 = 5  => 16 pairs (_) / D7 = 5  =>  0 pairs (X)
A9,D9: 5.. / A9 = 5  =>  0 pairs (X) / D9 = 5  => 16 pairs (_)
A4,A9: 5.. / A4 = 5  => 16 pairs (_) / A9 = 5  =>  0 pairs (X)
B4,B7: 5.. / B4 = 5  =>  0 pairs (X) / B7 = 5  => 16 pairs (_)
G1,I3: 6.. / G1 = 6  => 22 pairs (_) / I3 = 6  =>  0 pairs (X)
B5,I5: 6.. / B5 = 6  => 21 pairs (_) / I5 = 6  =>  0 pairs (X)
G1,G4: 6.. / G1 = 6  => 22 pairs (_) / G4 = 6  =>  0 pairs (X)
G1,H3: 7.. / G1 = 7  =>  0 pairs (X) / H3 = 7  => 22 pairs (_)
D4,D5: 7.. / D4 = 7  => 23 pairs (_) / D5 = 7  => 20 pairs (_)
A2,B2: 8.. / A2 = 8  => 20 pairs (_) / B2 = 8  =>  0 pairs (X)
D1,F1: 8.. / D1 = 8  =>  0 pairs (X) / F1 = 8  => 16 pairs (_)
D7,F8: 8.. / D7 = 8  => 16 pairs (_) / F8 = 8  =>  0 pairs (X)
B7,D7: 8.. / B7 = 8  =>  0 pairs (X) / D7 = 8  => 16 pairs (_)
A2,A8: 8.. / A2 = 8  => 20 pairs (_) / A8 = 8  =>  0 pairs (X)
D1,D7: 8.. / D1 = 8  =>  0 pairs (X) / D7 = 8  => 16 pairs (_)
F1,F8: 8.. / F1 = 8  => 16 pairs (_) / F8 = 8  =>  0 pairs (X)
B1,B3: 9.. / B1 = 9  => 15 pairs (_) / B3 = 9  => 23 pairs (_)
F8,D9: 9.. / F8 = 9  => 16 pairs (_) / D9 = 9  =>  0 pairs (X)
H8,G9: 9.. / H8 = 9  =>  0 pairs (X) / G9 = 9  => 16 pairs (_)
B3,D3: 9.. / B3 = 9  => 23 pairs (_) / D3 = 9  => 15 pairs (_)
F8,H8: 9.. / F8 = 9  => 16 pairs (_) / H8 = 9  =>  0 pairs (X)
D9,G9: 9.. / D9 = 9  =>  0 pairs (X) / G9 = 9  => 16 pairs (_)
F1,F8: 9.. / F1 = 9  =>  0 pairs (X) / F8 = 9  => 16 pairs (_)
I2,I4: 9.. / I2 = 9  => 20 pairs (_) / I4 = 9  => 21 pairs (_)
* DURATION: 0:01:03.432251  START: 01:21:32.592040  END: 01:22:36.024291 2019-05-01
* CP COUNT: (46)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A2,A9,B2,B7,C1,C3,D3,D4,D5,D7,D9,F1,F8,G1,G2,G9,H2,H3,H8,I3)
* ....3..52..5167.......528....8.13...9...845.....695.8.1.9.26437..637.1.5.37.41.68
* PAIR C1: 1,4 BLK 1
B1: 1,4,6,7,9                            # reduction candidate for 1,4
B1: 1,4                                  # 26 pairs
B1: 6,7,9                                # 20 pairs
* PAIR C1: 1,4 COL C
C6: 1,4,2,3                              # reduction candidate for 1,4
C6: 1,4 => SOLVED
* 714938652825167349693452871548213796962784513371695284159826437486379125237541968
C6: 2,3                                  # 23 pairs
* PAIR A2: 2,8 COL A
A8: 2,8,4                                # reduction candidate for 2,8
A8: 2,8 => CTR
* ..4839.52825167.4..934528...58.13...9.1.845.3372695.8.189526437246378195537941268
A8: 4                                    # 16 pairs
* PAIR B2: 2,8 COL B
B8: 2,8,4                                # reduction candidate for 2,8
B8: 4 => CTR
* ..4839.52825167.4..934528...58.13...9.1.845.3372695.8.189526437246378195537941268
B8: 2,8                                  # 16 pairs
* PAIR C3: 3,4 BLK 1
A3: 3,4,6,7                              # reduction candidate for 3,4
A3: 3,4 => CTR
* 6914387528251673..3749528165.8.136..96..8457171.69528.159826437486379125237541968
A3: 6,7                                  # 24 pairs
* PAIR C3: 3,4 COL C
C6: 3,4,1,2                              # reduction candidate for 3,4
C6: 3,4 => CTR
* ..1.3..52825167349..4952871548213796962784513.1.6952841.9.26437..637.125237541968
C6: 1,2                                  # 23 pairs
* PAIR F1: 8,9 BLK 2
D1: 8,9,4                                # reduction candidate for 8,9
D1: 8,9                                  # 23 pairs
D1: 4                                    # 15 pairs
* PAIR D3: 4,9 BLK 2
D1: 4,9,8                                # reduction candidate for 4,9
D1: 8 => CTR
* ...839.52825167.4..934528...58.13...9...845.33.269578.189526437246378195537941268
D1: 4,9                                  # 16 pairs
* PAIR D3: 4,9 ROW 3
B3: 4,9,6,7                              # reduction candidate for 4,9
B3: 6,7 => CTR
* 6914387528251673..3749528165.821367.9...845..7..69528.159826437486379125237541968
B3: 4,9                                  # 24 pairs
* PAIR G1: 6,7 ROW 1
A1: 6,7,4                                # reduction candidate for 6,7
A1: 6,7                                  # 21 pairs
B1: 6,7,1,4,9                            # reduction candidate for 6,7
B1: 6,7 => CTR
* ..1.3..52..5167....9.4528....8.13...9...845....469528.1.9.26437.4637.125237541968
B1: 1,4,9                                # 21 pairs
* PAIR G1: 6,7 COL G
G4: 6,7,2,9                              # reduction candidate for 6,7
G4: 2,9 => CTR
* ..1.3.652..51673....4952871..8.13...9.32845164126957831.9.26437.46379125237541968
G4: 6,7                                  # 23 pairs
* PAIR G2: 3,9 BLK 3
I2: 3,9,4                                # reduction candidate for 3,9
I2: 3,9                                  # 20 pairs
I2: 4                                    # 15 pairs
* PAIR H2: 4,9 BLK 3
I2: 4,9,3                                # reduction candidate for 4,9
I2: 3 => CTR
* ....3..52..5167.43....528....8.13..99.3.845....26953841.9.26437..637.195.37941268
I2: 4,9                                  # 21 pairs
* PAIR H2: 4,9 COL H
H4: 4,9,2,7                              # reduction candidate for 4,9
H4: 2,7 => CTR
* ..4839.52825167.4..934528...58.13...9.1.845.33.2695781189526437246378195537941268
H4: 4,9                                  # 16 pairs
* PAIR H3: 1,7 COL H
H5: 1,7,2                                # reduction candidate for 1,7
H5: 2 => CTR
* 6...39752..51679433...52816..8.1367996.78452...26953841.9.26437..637.195.37941268
H5: 1,7                                  # 21 pairs
* PAIR I3: 1,6 COL I
I5: 1,6,3                                # reduction candidate for 1,6
I5: 1,6 => CTR
* .91438.528251673..3.49528..5.8.132..9.32845....26957831598264374.6379125237541968
I5: 3                                    # 23 pairs
* PAIR D4: 2,7 ROW 4
G4: 2,7,6,9                              # reduction candidate for 2,7
G4: 2,7 => SOLVED
* 714938652825167349693452871548213796962784513371695284159826437486379125237541968
G4: 6,9                                  # 21 pairs
H4: 2,7,4,9                              # reduction candidate for 2,7
H4: 2,7 => CTR
* ..4839.52825167.4..934528...58.13...9.1.845.33.2695781189526437246378195537941268
H4: 4,9                                  # 16 pairs
* PAIR D5: 2,7 ROW 5
H5: 2,7,1                                # reduction candidate for 2,7
H5: 2,7 => CTR
* 6...39752..51679433...52816..8.136.996..845....26953841.9.26437..637.195.37941268
H5: 1                                    # 22 pairs
* PAIR H8: 2,9 COL H
H4: 2,9,4,7                              # reduction candidate for 2,9
H4: 2,9                                  # 22 pairs
H4: 4,7                                  # 21 pairs
* PAIR G9: 2,9 COL G
G4: 2,9,6,7                              # reduction candidate for 2,9
G4: 2,9 => CTR
* ..1.3.652..51673....4952871..8.13...9.32845164126957831.9.26437.46379125237541968
G4: 6,7                                  # 23 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060728-absurd-base-pr-000.dot
* REASONING
* PRF # C6: 1,4 => SOL
* DIS # A8: 2,8 => CTR => A8: 4
* DIS # B8: 4 => CTR => B8: 2,8
* DIS # A3: 3,4 => CTR => A3: 6,7
* DIS # C6: 3,4 => CTR => C6: 1,2
* DIS # D1: 8 => CTR => D1: 4,9
* DIS # B3: 6,7 => CTR => B3: 4,9
* DIS # B1: 6,7 => CTR => B1: 1,4,9
* DIS # G4: 2,9 => CTR => G4: 6,7
* DIS # I2: 3 => CTR => I2: 4,9
* DIS # H4: 2,7 => CTR => H4: 4,9
* DIS # H5: 2 => CTR => H5: 1,7
* DIS # I5: 1,6 => CTR => I5: 3
* PRF # G4: 2,7 => SOL
* DIS # H4: 2,7 => CTR => H4: 4,9
* DIS # H5: 2,7 => CTR => H5: 1
* DIS # G4: 2,9 => CTR => G4: 6,7
* CNT  17 HDP CHAINS /  43 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A2,A9,B2,B7,C1,C3,D3,D4,D5,D7,D9,F1,F8,G1,G2,G9,H2,H3,H8,I3)
* ....3..52..5167.......528....8.13...9...845.....695.8.1.9.26437..637.1.5.37.41.68
* PAIR C1: 1,4 BLK 1
B1: 1,4,6,7,9                            # reduction candidate for 1,4
B1: 1,4                                  # 26 pairs
B1: 6,7,9                                # 20 pairs
* PAIR C1: 1,4 COL C
C6: 1,4,2,3                              # reduction candidate for 1,4
C6: 1,4 => SOLVED
* 714938652825167349693452871548213796962784513371695284159826437486379125237541968
* DURATION: 0:00:03.058845  START: 01:23:08.418248  END: 01:23:11.477093 2019-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060728-absurd-base-pr-001.dot
* REASONING
* PRF # C6: 1,4 => SOL
* STA C6: 1,4
* CNT   1 HDP CHAINS /   3 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Jul&YEAR=2006, 20060728, absurd

Solution

position: 714938652825167349693452871548213796962784513371695284159826437486379125237541968 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 # B1: 1,4 => UNS
* INC # B1: 6,7,9 => UNS
* PRF # C6: 1,4 => SOL
* INC # C6: 2,3 => UNS
* DIS # A8: 2,8 => CTR => A8: 4
* INC # A8: 4 => UNS
* INC # B8: 2,8 => UNS
* DIS # B8: 4 => CTR => B8: 2,8
* DIS # A3: 3,4 => CTR => A3: 6,7
* INC # A3: 6,7 => UNS
* DIS # C6: 3,4 => CTR => C6: 1,2
* INC # C6: 1,2 => UNS
* INC # D1: 8,9 => UNS
* INC # D1: 4 => UNS
* INC # D1: 4,9 => UNS
* DIS # D1: 8 => CTR => D1: 4,9
* INC # B3: 4,9 => UNS
* DIS # B3: 6,7 => CTR => B3: 4,9
* INC # A1: 6,7 => UNS
* DIS # B1: 6,7 => CTR => B1: 1,4,9
* INC # B1: 1,4,9 => UNS
* INC # G4: 6,7 => UNS
* DIS # G4: 2,9 => CTR => G4: 6,7
* INC # I2: 3,9 => UNS
* INC # I2: 4 => UNS
* INC # I2: 4,9 => UNS
* DIS # I2: 3 => CTR => I2: 4,9
* INC # H4: 4,9 => UNS
* DIS # H4: 2,7 => CTR => H4: 4,9
* INC # H5: 1,7 => UNS
* DIS # H5: 2 => CTR => H5: 1,7
* DIS # I5: 1,6 => CTR => I5: 3
* INC # I5: 3 => UNS
* PRF # G4: 2,7 => SOL
* INC # G4: 6,9 => UNS
* DIS # H4: 2,7 => CTR => H4: 4,9
* INC # H4: 4,9 => UNS
* DIS # H5: 2,7 => CTR => H5: 1
* INC # H5: 1 => UNS
* INC # H4: 2,9 => UNS
* INC # H4: 4,7 => UNS
* DIS # G4: 2,9 => CTR => G4: 6,7
* INC # G4: 6,7 => UNS
* CNT  43 HDP CHAINS /  43 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # B1: 1,4 => UNS
* INC # B1: 6,7,9 => UNS
* PRF # C6: 1,4 => SOL
* STA C6: 1,4
* CNT   3 HDP CHAINS /   3 HYP OPENED