Analysis of zz-www.sudokuoftheday.co.uk-20060715-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: 4.3..65.2..53.8...9....27..3....4.2....7....626.........1983.6.......9.......5..4 initial

Autosolve

position: 4.31.65.2.253.864.9.6..27..3....4.2....72...626..3.....4198326......79.......5..4 autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # I3: 1,8 => CTR => I3: 3
* DIS # H6: 8,9 => CTR => H6: 1,5,7
* DIS # B5: 1,9 => CTR => B5: 5
* DIS # H5: 1,9 => CTR => H5: 3,5,8
* DIS # H6: 5,8 => CTR => H6: 1,7,9
* DIS # H6: 1,9 => CTR => H6: 5,7,8
* DIS # I4: 1,8 => CTR => I4: 5,7,9
* PRF # G5: 1,8 => SOL
* DIS # H5: 1,8 => CTR => H5: 3,5,9
* DIS # G6: 1,8 => CTR => G6: 4
* DIS # H6: 1,8 => CTR => H6: 5,7,9
* DIS # I6: 1,8 => CTR => I6: 5,7,9
* PRF # G9: 3 => SOL
* DIS # C9: 2,8 => CTR => C9: 7,9
* PRF # C9: 7,9 => SOL
* CNT  15 HDP CHAINS /  46 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 # I3: 1,8 => CTR => I3: 3
* DIS I3: 3 # B5: 1,9 => CTR => B5: 5
* DIS I3: 3 + B5: 5 # H5: 1,9 => CTR => H5: 3
* PRF I3: 3 + B5: 5 + H5: 3 => SOL
* STA I3: 3 + B5: 5 + H5: 3
* CNT   4 HDP CHAINS /   8 HYP OPENED

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

Details

Positions

4.3..65.2..53.8...9....27..3....4.2....7....626.........1983.6.......9.......5..4 initial
4.31.65.2.253.864.9.6..27..3....4.2....72...626..3.....4198326......79.......5..4 autosolve
483176592725398641916542783378654129154729836269831475541983267632417958897265314 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (20)
B1: 7,8
A2: 1,7
B3: 1,8
E1: 7,9
E2: 7,9
D3: 4,5
E3: 4,5
H1: 8,9
I2: 1,9
E4: 5,6
F5: 1,9
D6: 5,8
F6: 1,9
G4: 1,8
A7: 5,7
B8: 3,5
C8: 2,8
D9: 2,6
E9: 1,6
I7: 5,7

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
A2,B3: 1.. / A2 = 1  => 19 pairs (_) / B3 = 1  =>  0 pairs (*)
F5,F6: 1.. / F5 = 1  =>  0 pairs (X) / F6 = 1  => 21 pairs (_)
E8,E9: 1.. / E8 = 1  => 18 pairs (_) / E9 = 1  => 21 pairs (_)
A2,I2: 1.. / A2 = 1  => 19 pairs (_) / I2 = 1  =>  0 pairs (*)
A2,A5: 1.. / A2 = 1  => 19 pairs (_) / A5 = 1  =>  0 pairs (*)
C8,C9: 2.. / C8 = 2  => 19 pairs (_) / C9 = 2  =>  0 pairs (X)
D8,D9: 2.. / D8 = 2  =>  0 pairs (X) / D9 = 2  => 19 pairs (_)
C8,D8: 2.. / C8 = 2  => 19 pairs (_) / D8 = 2  =>  0 pairs (X)
C9,D9: 2.. / C9 = 2  =>  0 pairs (X) / D9 = 2  => 19 pairs (_)
H3,I3: 3.. / H3 = 3  =>  0 pairs (X) / I3 = 3  => 21 pairs (_)
G5,H5: 3.. / G5 = 3  => 21 pairs (_) / H5 = 3  =>  0 pairs (*)
B8,B9: 3.. / B8 = 3  => 23 pairs (_) / B9 = 3  =>  0 pairs (X)
G5,G9: 3.. / G5 = 3  => 21 pairs (_) / G9 = 3  =>  0 pairs (*)
I3,I8: 3.. / I3 = 3  => 21 pairs (_) / I8 = 3  =>  0 pairs (X)
D3,E3: 4.. / D3 = 4  => 19 pairs (_) / E3 = 4  => 16 pairs (_)
C5,C6: 4.. / C5 = 4  => 20 pairs (_) / C6 = 4  =>  0 pairs (X)
G5,G6: 4.. / G5 = 4  =>  0 pairs (X) / G6 = 4  => 20 pairs (_)
D8,E8: 4.. / D8 = 4  => 16 pairs (_) / E8 = 4  => 19 pairs (_)
C5,G5: 4.. / C5 = 4  => 20 pairs (_) / G5 = 4  =>  0 pairs (X)
C6,G6: 4.. / C6 = 4  =>  0 pairs (X) / G6 = 4  => 20 pairs (_)
D3,D8: 4.. / D3 = 4  => 19 pairs (_) / D8 = 4  => 16 pairs (_)
E3,E8: 4.. / E3 = 4  => 16 pairs (_) / E8 = 4  => 19 pairs (_)
D3,E3: 5.. / D3 = 5  => 16 pairs (_) / E3 = 5  => 19 pairs (_)
A7,I7: 5.. / A7 = 5  => 23 pairs (_) / I7 = 5  =>  0 pairs (X)
E3,E4: 5.. / E3 = 5  => 19 pairs (_) / E4 = 5  => 16 pairs (_)
D4,E4: 6.. / D4 = 6  => 16 pairs (_) / E4 = 6  => 19 pairs (_)
A8,A9: 6.. / A8 = 6  => 23 pairs (_) / A9 = 6  => 21 pairs (_)
B1,A2: 7.. / B1 = 7  => 19 pairs (_) / A2 = 7  =>  0 pairs (*)
E1,E2: 7.. / E1 = 7  =>  0 pairs (*) / E2 = 7  =>  0 pairs (X)
I7,H9: 7.. / I7 = 7  => 23 pairs (_) / H9 = 7  =>  0 pairs (X)
B1,E1: 7.. / B1 = 7  => 19 pairs (_) / E1 = 7  =>  0 pairs (*)
A2,E2: 7.. / A2 = 7  =>  0 pairs (*) / E2 = 7  =>  0 pairs (X)
A7,I7: 7.. / A7 = 7  =>  0 pairs (X) / I7 = 7  => 23 pairs (_)
H6,H9: 7.. / H6 = 7  => 23 pairs (_) / H9 = 7  =>  0 pairs (X)
B1,B3: 8.. / B1 = 8  =>  0 pairs (*) / B3 = 8  =>  0 pairs (X)
D4,D6: 8.. / D4 = 8  => 18 pairs (_) / D6 = 8  => 21 pairs (_)
B1,H1: 8.. / B1 = 8  =>  0 pairs (*) / H1 = 8  =>  0 pairs (X)
E1,E2: 9.. / E1 = 9  => 19 pairs (_) / E2 = 9  =>  0 pairs (*)
H1,I2: 9.. / H1 = 9  =>  0 pairs (*) / I2 = 9  =>  0 pairs (X)
F5,F6: 9.. / F5 = 9  => 21 pairs (_) / F6 = 9  =>  0 pairs (X)
B9,C9: 9.. / B9 = 9  => 23 pairs (_) / C9 = 9  =>  0 pairs (X)
E1,H1: 9.. / E1 = 9  => 19 pairs (_) / H1 = 9  =>  0 pairs (*)
E2,I2: 9.. / E2 = 9  =>  0 pairs (*) / I2 = 9  =>  0 pairs (X)
* DURATION: 0:00:51.793842  START: 00:42:02.576868  END: 00:42:54.370710 2019-05-01
* CP COUNT: (43)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A2,A7,B1,B3,B8,C8,D3,D6,D9,E1,E2,E3,E4,E9,F5,F6,G4,H1,I2,I7)
* 4.31.65.2.253.864.9.6..27..3....4.2....72...626..3.....4198326......79.......5..4
* PAIR B3: 1,8 ROW 3
H3: 1,8,3                                # reduction candidate for 1,8
H3: 1,8                                  # 21 pairs
I3: 1,8,3                                # reduction candidate for 1,8
I3: 1,8 => CTR
* 4.31.65.2.253.864.9.6..273.3....4.2.5.472.38626..3.45.741983265852..7913639215874
I3: 3                                    # 21 pairs
* PAIR H1: 8,9 COL H
H5: 8,9,1,3,5                            # reduction candidate for 8,9
H5: 8,9                                  # 23 pairs
H6: 8,9,1,5,7                            # reduction candidate for 8,9
H6: 8,9 => CTR
* 473196582125378649986..27..3....4.2....72..5626.53..9.74198326553...7918.....5.74
H6: 1,5,7                                # 20 pairs
* PAIR I2: 1,9 COL I
I4: 1,9,5,7,8                            # reduction candidate for 1,9
I4: 1,9                                  # 22 pairs
I6: 1,9,5,7,8                            # reduction candidate for 1,9
I6: 1,9                                  # 25 pairs
* PAIR E4: 5,6 BLK 5
D4: 5,6,8                                # reduction candidate for 5,6
D4: 5,6                                  # 21 pairs
D4: 8                                    # 18 pairs
* PAIR F5: 1,9 ROW 5
B5: 1,9,5                                # reduction candidate for 1,9
B5: 1,9 => CTR
* 473196582125378649986..27..3....4.2..1.729.5626.531.9.74198326553...7918.....5.74
B5: 5                                    # 23 pairs
H5: 1,9,3,5,8                            # reduction candidate for 1,9
H5: 1,9 => CTR
* 4.31.65.2125378649986..2713319..482785472139626783945174198326553..1798......5.34
H5: 3,5,8                                # 20 pairs
* PAIR D6: 5,8 BLK 5
D4: 5,8,6                                # reduction candidate for 5,8
D4: 5,8                                  # 19 pairs
D4: 6                                    # 16 pairs
* PAIR D6: 5,8 ROW 6
H6: 5,8,1,7,9                            # reduction candidate for 5,8
H6: 5,8 => CTR
* 473196582125378649986..27..3....4.2....72139626.839451741983265.....79...392.5174
H6: 1,7,9                                # 20 pairs
I6: 5,8,1,7,9                            # reduction candidate for 5,8
I6: 5,8                                  # 22 pairs
* PAIR F6: 1,9 ROW 6
H6: 1,9,5,7,8                            # reduction candidate for 1,9
H6: 1,9 => CTR
* 473196582125378649986..27..3....4.2....72..5626.53..9.74198326553...7918.....5.74
H6: 5,7,8                                # 20 pairs
I6: 1,9,5,7,8                            # reduction candidate for 1,9
I6: 1,9                                  # 25 pairs
* PAIR G4: 1,8 BLK 6
I4: 1,8,5,7,9                            # reduction candidate for 1,8
I4: 1,8 => CTR
* 4.31.65.2.253.864.9.6..27..3....4.2....72...626..3.....4198326......79.......5..4
I4: 5,7,9                                # 20 pairs
G5: 1,8,3,4                              # reduction candidate for 1,8
G5: 1,8 => SOLVED
* 483176592725398641916542783378654129154729836269831475541983267632417958897265314
G5: 3,4                                  # 21 pairs
H5: 1,8,3,5,9                            # reduction candidate for 1,8
H5: 1,8 => CTR
* 4.31.6592.25398641916..27..3....412.15472938626..314...4198326..3...79.8.....5..4
H5: 3,5,9                                # 20 pairs
G6: 1,8,4                                # reduction candidate for 1,8
G6: 1,8 => CTR
* 4.31.65.2.253.8641916..27833....412.158729436264.318...4198326..32..79.88..265314
G6: 4                                    # 20 pairs
H6: 1,8,5,7,9                            # reduction candidate for 1,8
H6: 1,8 => CTR
* 473196582.253.864.9.6..27..3....4.2....72...626..3....741983265.....79.......5.74
H6: 5,7,9                                # 20 pairs
I6: 1,8,5,7,9                            # reduction candidate for 1,8
I6: 1,8 => CTR
* 473196582125378649986..27..3....4.2.8.472.3.6267.3.4...4198326..3...79...9...5..4
I6: 5,7,9                                # 20 pairs
* PAIR G4: 1,8 COL G
G9: 1,8,3                                # reduction candidate for 1,8
G9: 3 => SOLVED
* 483176592725398641916542783378654129154729836269831475541983267632417958897265314
G9: 1,8                                  # 21 pairs
* PAIR B8: 3,5 ROW 8
H8: 3,5,1,8                              # reduction candidate for 3,5
H8: 3,5                                  # 24 pairs
I8: 3,5,1,8                              # reduction candidate for 3,5
I8: 3,5                                  # 23 pairs
* PAIR C8: 2,8 BLK 7
C9: 2,8,7,9                              # reduction candidate for 2,8
C9: 2,8 => CTR
* 473196582125378649986..27133.9..4.278.472...6267.3.4..741983265.3...79...9...5..4
C9: 7,9 => SOLVED
* 483176592725398641916542783378654129154729836269831475541983267632417958897265314
* PAIR D9: 2,6 BLK 8
D8: 2,6,4                                # reduction candidate for 2,6
D8: 2,6                                  # 19 pairs
D8: 4                                    # 16 pairs
* PAIR E9: 1,6 BLK 8
E8: 1,6,4                                # reduction candidate for 1,6
E8: 4                                    # 19 pairs
E8: 1,6                                  # 16 pairs
* PAIR I7: 5,7 COL I
I4: 5,7,1,8,9                            # reduction candidate for 5,7
I4: 5,7                                  # 23 pairs
I6: 5,7,1,8,9                            # reduction candidate for 5,7
I6: 5,7                                  # 21 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060715-absurd-base-pr-000.dot
* REASONING
* DIS # I3: 1,8 => CTR => I3: 3
* DIS # H6: 8,9 => CTR => H6: 1,5,7
* DIS # B5: 1,9 => CTR => B5: 5
* DIS # H5: 1,9 => CTR => H5: 3,5,8
* DIS # H6: 5,8 => CTR => H6: 1,7,9
* DIS # H6: 1,9 => CTR => H6: 5,7,8
* DIS # I4: 1,8 => CTR => I4: 5,7,9
* PRF # G5: 1,8 => SOL
* DIS # H5: 1,8 => CTR => H5: 3,5,9
* DIS # G6: 1,8 => CTR => G6: 4
* DIS # H6: 1,8 => CTR => H6: 5,7,9
* DIS # I6: 1,8 => CTR => I6: 5,7,9
* PRF # G9: 3 => SOL
* DIS # C9: 2,8 => CTR => C9: 7,9
* PRF # C9: 7,9 => SOL
* CNT  15 HDP CHAINS /  46 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A2,A7,B1,B3,B8,C8,D3,D6,D9,E1,E2,E3,E4,E9,F5,F6,G4,H1,I2,I7)
* 4.31.65.2.253.864.9.6..27..3....4.2....72...626..3.....4198326......79.......5..4
* PAIR B3: 1,8 ROW 3
H3: 1,8,3                                # reduction candidate for 1,8
H3: 1,8                                  # 21 pairs
I3: 1,8,3                                # reduction candidate for 1,8
I3: 1,8 => CTR
* 4.31.65.2.253.864.9.6..273.3....4.2.5.472.38626..3.45.741983265852..7913639215874
* RESTART
* PAIR RESTART
* PAIR I2: 1,9 COL I
I4: 1,9,5,7,8                            # reduction candidate for 1,9
I4: 1,9                                  # 23 pairs
I6: 1,9,5,7,8                            # reduction candidate for 1,9
I6: 1,9                                  # 27 pairs
* PAIR E4: 5,6 BLK 5
D4: 5,6,8                                # reduction candidate for 5,6
D4: 8                                    # 22 pairs
D4: 5,6                                  # 22 pairs
* PAIR F5: 1,9 ROW 5
B5: 1,9,5                                # reduction candidate for 1,9
B5: 1,9 => CTR
* 473196582125378649986..271339...4.2.5..729..626..31.9.741983265.....793..392.5.74
H5: 1,9,3                                # reduction candidate for 1,9
H5: 1,9 => CTR
* 473196582.253.864.9.6..27.33....4.2.85472.3.6269.3147.54198326763...795.79...5.34
H5: 3 => SOLVED
* 483176592725398641916542783378654129154729836269831475541983267632417958897265314
* DURATION: 0:00:06.570908  START: 00:43:22.972162  END: 00:43:29.543070 2019-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060715-absurd-base-pr-001.dot
* REASONING
* DIS # I3: 1,8 => CTR => I3: 3
* DIS I3: 3 # B5: 1,9 => CTR => B5: 5
* DIS I3: 3 + B5: 5 # H5: 1,9 => CTR => H5: 3
* PRF I3: 3 + B5: 5 + H5: 3 => SOL
* STA I3: 3 + B5: 5 + H5: 3
* CNT   4 HDP CHAINS /   8 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Jul&YEAR=2006, 20060715, absurd

Solution

position: 483176592725398641916542783378654129154729836269831475541983267632417958897265314 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 # H3: 1,8 => UNS
* DIS # I3: 1,8 => CTR => I3: 3
* INC # I3: 3 => UNS
* INC # H5: 8,9 => UNS
* DIS # H6: 8,9 => CTR => H6: 1,5,7
* INC # H6: 1,5,7 => UNS
* INC # I4: 1,9 => UNS
* INC # I6: 1,9 => UNS
* INC # D4: 5,6 => UNS
* INC # D4: 8 => UNS
* DIS # B5: 1,9 => CTR => B5: 5
* INC # B5: 5 => UNS
* DIS # H5: 1,9 => CTR => H5: 3,5,8
* INC # H5: 3,5,8 => UNS
* INC # D4: 5,8 => UNS
* INC # D4: 6 => UNS
* DIS # H6: 5,8 => CTR => H6: 1,7,9
* INC # H6: 1,7,9 => UNS
* INC # I6: 5,8 => UNS
* DIS # H6: 1,9 => CTR => H6: 5,7,8
* INC # H6: 5,7,8 => UNS
* INC # I6: 1,9 => UNS
* DIS # I4: 1,8 => CTR => I4: 5,7,9
* INC # I4: 5,7,9 => UNS
* PRF # G5: 1,8 => SOL
* INC # G5: 3,4 => UNS
* DIS # H5: 1,8 => CTR => H5: 3,5,9
* INC # H5: 3,5,9 => UNS
* DIS # G6: 1,8 => CTR => G6: 4
* INC # G6: 4 => UNS
* DIS # H6: 1,8 => CTR => H6: 5,7,9
* INC # H6: 5,7,9 => UNS
* DIS # I6: 1,8 => CTR => I6: 5,7,9
* INC # I6: 5,7,9 => UNS
* INC # G9: 1,8 => UNS
* PRF # G9: 3 => SOL
* INC # H8: 3,5 => UNS
* INC # I8: 3,5 => UNS
* DIS # C9: 2,8 => CTR => C9: 7,9
* PRF # C9: 7,9 => SOL
* INC # D8: 2,6 => UNS
* INC # D8: 4 => UNS
* INC # E8: 1,6 => UNS
* INC # E8: 4 => UNS
* INC # I4: 5,7 => UNS
* INC # I6: 5,7 => UNS
* CNT  46 HDP CHAINS /  46 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # H3: 1,8 => UNS
* DIS # I3: 1,8 => CTR => I3: 3
* INC I3: 3 # I4: 1,9 => UNS
* INC I3: 3 # I6: 1,9 => UNS
* INC I3: 3 # D4: 5,6 => UNS
* INC I3: 3 # D4: 8 => UNS
* DIS I3: 3 # B5: 1,9 => CTR => B5: 5
* DIS I3: 3 + B5: 5 # H5: 1,9 => CTR => H5: 3
* PRF I3: 3 + B5: 5 + H5: 3 => SOL
* STA I3: 3 + B5: 5 + H5: 3
* CNT   9 HDP CHAINS /   8 HYP OPENED