Analysis of zz-www.sudokuoftheday.co.uk-20060403-absurd-base.sdk

Contents

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

level: medium

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

position: .4..6......5.....99..2........18.2.3....75..8...34......34..65...1...9...6.5.7.34 initial

Autosolve

position: .4..6......5.....99..25....5..18.2.3....75..8...342.....34..65.451...9...6.5.7.34 autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # D1: 9 => CTR => D1: 7,8
* DIS # A2: 7,8 => CTR => A2: 1,2,3,6
* DIS # F1: 1,3 => CTR => F1: 8,9
* DIS # A2: 1,3 => CTR => A2: 2,6,7,8
* DIS # C4: 7,9 => CTR => C4: 4,6
* DIS # C4: 6,9 => CTR => C4: 4,7
* DIS # G2: 1,4 => CTR => G2: 3,7,8
* DIS # G3: 1,4 => CTR => G3: 3,7,8
* DIS # A2: 2,8 => CTR => A2: 1,3,6,7
* DIS # F1: 1,8 => CTR => F1: 3,9
* DIS # F8: 6,8 => CTR => F8: 3
* DIS # H8: 2,7 => CTR => H8: 8
* DIS # I1: 2,7 => CTR => I1: 1,5
* CNT  13 HDP CHAINS /  57 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 # D1: 9 => CTR => D1: 7,8
* DIS D1: 7,8 # A2: 7,8 => CTR => A2: 1,2,3,6
* DIS D1: 7,8 + A2: 1,2,3,6 # A2: 1,3 => CTR => A2: 2,6
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 # C4: 7,9 => CTR => C4: 4
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 # G2: 1,4 => CTR => G2: 3,7,8
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 # G3: 1,4 => CTR => G3: 3,7,8
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 # A1: 2,8 => CTR => A1: 1,3,7
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 # H8: 2,7 => CTR => H8: 8
* PRF D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 + H8: 8 # B3: 1,3 => SOL
* STA D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 + H8: 8 + B3: 1,3
* CNT   9 HDP CHAINS /  40 HYP OPENED

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

Details

Positions

.4..6......5.....99..2........18.2.3....75..8...34......34..65...1...9...6.5.7.34 initial
.4..6......5.....99..25....5..18.2.3....75..8...342.....34..65.451...9...6.5.7.34 autosolve
347869521625731849918254376574186293236975418189342765793418652451623987862597134 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (13)
D2: 7,8
E2: 1,3
B4: 7,9
F4: 6,9
D5: 6,9
G5: 1,4
A9: 2,8
F7: 1,8
D8: 6,8
E8: 2,3
I7: 1,2
I8: 2,7
G9: 1,8

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
I7,G9: 1.. / I7 = 1  =>  0 pairs (X) / G9 = 1  => 14 pairs (_)
E9,G9: 1.. / E9 = 1  =>  0 pairs (X) / G9 = 1  => 14 pairs (_)
A5,B5: 3.. / A5 = 3  => 13 pairs (_) / B5 = 3  => 13 pairs (_)
E8,F8: 3.. / E8 = 3  =>  0 pairs (X) / F8 = 3  => 14 pairs (_)
E2,E8: 3.. / E2 = 3  => 14 pairs (_) / E8 = 3  =>  0 pairs (X)
F2,F3: 4.. / F2 = 4  => 13 pairs (_) / F3 = 4  => 13 pairs (_)
C4,C5: 4.. / C4 = 4  => 13 pairs (_) / C5 = 4  =>  0 pairs (X)
C4,H4: 4.. / C4 = 4  => 13 pairs (_) / H4 = 4  =>  0 pairs (X)
G1,I1: 5.. / G1 = 5  => 15 pairs (_) / I1 = 5  => 15 pairs (_)
G6,I6: 5.. / G6 = 5  => 15 pairs (_) / I6 = 5  => 15 pairs (_)
G1,G6: 5.. / G1 = 5  => 15 pairs (_) / G6 = 5  => 15 pairs (_)
I1,I6: 5.. / I1 = 5  => 15 pairs (_) / I6 = 5  => 15 pairs (_)
A2,C3: 6.. / A2 = 6  => 14 pairs (_) / C3 = 6  =>  0 pairs (X)
F4,D5: 6.. / F4 = 6  => 12 pairs (_) / D5 = 6  =>  0 pairs (X)
D8,F8: 6.. / D8 = 6  => 12 pairs (_) / F8 = 6  =>  0 pairs (X)
A2,H2: 6.. / A2 = 6  => 14 pairs (_) / H2 = 6  =>  0 pairs (X)
D5,D8: 6.. / D5 = 6  =>  0 pairs (X) / D8 = 6  => 12 pairs (_)
F4,F8: 6.. / F4 = 6  => 12 pairs (_) / F8 = 6  =>  0 pairs (X)
I3,I6: 6.. / I3 = 6  => 14 pairs (_) / I6 = 6  =>  0 pairs (X)
D1,D2: 7.. / D1 = 7  => 11 pairs (_) / D2 = 7  => 13 pairs (_)
A7,B7: 7.. / A7 = 7  => 13 pairs (_) / B7 = 7  => 16 pairs (_)
H8,I8: 7.. / H8 = 7  =>  0 pairs (X) / I8 = 7  => 14 pairs (_)
H8,G9: 8.. / H8 = 8  => 14 pairs (_) / G9 = 8  =>  0 pairs (X)
D1,F1: 9.. / D1 = 9  =>  0 pairs (X) / F1 = 9  => 12 pairs (_)
F4,D5: 9.. / F4 = 9  =>  0 pairs (X) / D5 = 9  => 12 pairs (_)
B7,C9: 9.. / B7 = 9  => 14 pairs (_) / C9 = 9  => 14 pairs (_)
E7,E9: 9.. / E7 = 9  => 14 pairs (_) / E9 = 9  => 14 pairs (_)
B7,E7: 9.. / B7 = 9  => 14 pairs (_) / E7 = 9  => 14 pairs (_)
C9,E9: 9.. / C9 = 9  => 14 pairs (_) / E9 = 9  => 14 pairs (_)
D1,D5: 9.. / D1 = 9  =>  0 pairs (X) / D5 = 9  => 12 pairs (_)
F1,F4: 9.. / F1 = 9  => 12 pairs (_) / F4 = 9  =>  0 pairs (X)
* DURATION: 0:00:26.939483  START: 22:07:02.888912  END: 22:07:29.828395 2019-04-30
* CP COUNT: (31)
* CLUE FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A9,B4,D2,D5,D8,E2,E8,F4,F7,G5,G9,I7,I8)
* .4..6......5.....99..25....5..18.2.3....75..8...342.....34..65.451...9...6.5.7.34
* PAIR D2: 7,8 BLK 2
D1: 7,8,9                                # reduction candidate for 7,8
D1: 9 => CTR
* .4.96......57....99..25....57.1892.3...675..8...342...78349165.4518.69...6.5.7834
D1: 7,8                                  # 12 pairs
* PAIR D2: 7,8 ROW 2
A2: 7,8,1,2,3,6                          # reduction candidate for 7,8
A2: 7,8 => CTR
* 34..69..5.25....6991625...75.41862.3632975..81..342..6..34..65.4516..9...6.5.7.34
A2: 1,2,3,6                              # 13 pairs
B2: 7,8,1,2,3                            # reduction candidate for 7,8
B2: 7,8                                  # 18 pairs
G2: 7,8,1,3,4                            # reduction candidate for 7,8
G2: 7,8                                  # 14 pairs
H2: 7,8,1,2,4,6                          # reduction candidate for 7,8
H2: 7,8                                  # 20 pairs
* PAIR E2: 1,3 BLK 2
F1: 1,3,8,9                              # reduction candidate for 1,3
F1: 1,3 => CTR
* .4.96......57....99..25....57.1892.3...675..8...342...78349165.4518.69...6.5.7834
F1: 8,9                                  # 14 pairs
F2: 1,3,4,8                              # reduction candidate for 1,3
F2: 1,3                                  # 17 pairs
F3: 1,3,4,8                              # reduction candidate for 1,3
F3: 1,3                                  # 15 pairs
* PAIR E2: 1,3 ROW 2
A2: 1,3,2,6,7,8                          # reduction candidate for 1,3
A2: 1,3 => CTR
* 14..69325325.1..699.625....5.41862.3632975..8...3425.6..34..65.4516..987.6.5.7134
A2: 2,6,7,8                              # 13 pairs
B2: 1,3,2,7,8                            # reduction candidate for 1,3
B2: 1,3                                  # 17 pairs
G2: 1,3,4,7,8                            # reduction candidate for 1,3
G2: 1,3                                  # 17 pairs
* PAIR B4: 7,9 BLK 4
C4: 7,9,4,6                              # reduction candidate for 7,9
C4: 7,9 => CTR
* .4..6......5.3...99..25....5..186243..4975168...342.9...349865145162397..6.517834
C4: 4,6                                  # 14 pairs
B6: 7,9,1,8                              # reduction candidate for 7,9
B6: 7,9                                  # 18 pairs
C6: 7,9,6,8                              # reduction candidate for 7,9
C6: 7,9                                  # 16 pairs
* PAIR B4: 7,9 ROW 4
H4: 7,9,4,6                              # reduction candidate for 7,9
H4: 7,9                                  # 14 pairs
H4: 4,6                                  # 14 pairs
* PAIR B4: 7,9 COL B
B7: 7,9,2,8                              # reduction candidate for 7,9
B7: 7,9                                  # 15 pairs
B7: 2,8                                  # 15 pairs
* PAIR F4: 6,9 ROW 4
C4: 6,9,4,7                              # reduction candidate for 6,9
C4: 6,9 => CTR
* .4..6......5.3...99..25....57.18.243..4.751.8...342...7834..651451...9...6.517834
C4: 4,7                                  # 14 pairs
H4: 6,9,4,7                              # reduction candidate for 6,9
H4: 6,9                                  # 13 pairs
* PAIR D5: 6,9 ROW 5
C5: 6,9,2,4                              # reduction candidate for 6,9
C5: 6,9                                  # 18 pairs
H5: 6,9,1,4                              # reduction candidate for 6,9
H5: 6,9                                  # 15 pairs
* PAIR G5: 1,4 BLK 6
H5: 1,4,6,9                              # reduction candidate for 1,4
H5: 6,9                                  # 15 pairs
H5: 1,4                                  # 15 pairs
* PAIR G5: 1,4 COL G
G2: 1,4,3,7,8                            # reduction candidate for 1,4
G2: 1,4 => CTR
* .4..6......5.3...99..25....5..18.2.3....75..8...342.....349865145162397..6.517834
G2: 3,7,8                                # 13 pairs
G3: 1,4,3,7,8                            # reduction candidate for 1,4
G3: 1,4 => CTR
* .4..6......5.3.7.993725...65..18.2.33...75..8...3425.77834..651451...9...6.517834
G3: 3,7,8                                # 13 pairs
* PAIR A9: 2,8 BLK 7
A7: 2,8,7                                # reduction candidate for 2,8
A7: 2,8                                  # 16 pairs
B7: 2,8,7,9                              # reduction candidate for 2,8
B7: 2,8                                  # 15 pairs
C9: 2,8,9                                # reduction candidate for 2,8
C9: 2,8                                  # 14 pairs
* PAIR A9: 2,8 COL A
A1: 2,8,1,3,7                            # reduction candidate for 2,8
A1: 2,8                                  # 15 pairs
A2: 2,8,1,3,6,7                          # reduction candidate for 2,8
A2: 2,8 => CTR
* 34..69125..5....699.625...75.41862.36329754181..3425.67.34..6514516..972.6.517834
A2: 1,3,6,7                              # 13 pairs
* PAIR F7: 1,8 COL F
F1: 1,8,3,9                              # reduction candidate for 1,8
F1: 1,8 => CTR
* .4.96......57....99..25....57.1892.3...675..8...342...78349165.4518.69...6.5.7834
F1: 3,9                                  # 14 pairs
F2: 1,8,3,4                              # reduction candidate for 1,8
F2: 1,8                                  # 16 pairs
F3: 1,8,3,4                              # reduction candidate for 1,8
F3: 1,8                                  # 16 pairs
* PAIR D8: 6,8 BLK 8
F8: 6,8,3                                # reduction candidate for 6,8
F8: 6,8 => CTR
* .4..6......5.1...99..25....5..18.2.3....75..8...342.....34.1652451.3.9.7.6.527134
F8: 3                                    # 14 pairs
* PAIR I7: 1,2 ROW 7
E7: 1,2,9                                # reduction candidate for 1,2
E7: 9                                    # 14 pairs
E7: 1,2                                  # 14 pairs
* PAIR I7: 1,2 COL I
I1: 1,2,5,7                              # reduction candidate for 1,2
I1: 1,2                                  # 16 pairs
I1: 5,7                                  # 15 pairs
* PAIR I8: 2,7 BLK 9
H8: 2,7,8                                # reduction candidate for 2,7
H8: 2,7 => CTR
* .4..6......5.....99..25....5..18.2.3....75..8...342.....34..651451...9..269517834
H8: 8                                    # 14 pairs
* PAIR I8: 2,7 COL I
I1: 2,7,1,5                              # reduction candidate for 2,7
I1: 2,7 => CTR
* .4..6.5..6.5.3...99..25.3.65..18.2.3.3..75..8...342..5..349865145162397..6.517834
I1: 1,5                                  # 15 pairs
* PAIR G9: 1,8 COL G
G1: 1,8,3,5,7                            # reduction candidate for 1,8
G1: 1,8                                  # 17 pairs
G2: 1,8,3,4,7                            # reduction candidate for 1,8
G2: 1,8                                  # 15 pairs
G3: 1,8,3,4,7                            # reduction candidate for 1,8
G3: 1,8                                  # 15 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060403-absurd-base-pr-000.dot
* REASONING
* DIS # D1: 9 => CTR => D1: 7,8
* DIS # A2: 7,8 => CTR => A2: 1,2,3,6
* DIS # F1: 1,3 => CTR => F1: 8,9
* DIS # A2: 1,3 => CTR => A2: 2,6,7,8
* DIS # C4: 7,9 => CTR => C4: 4,6
* DIS # C4: 6,9 => CTR => C4: 4,7
* DIS # G2: 1,4 => CTR => G2: 3,7,8
* DIS # G3: 1,4 => CTR => G3: 3,7,8
* DIS # A2: 2,8 => CTR => A2: 1,3,6,7
* DIS # F1: 1,8 => CTR => F1: 3,9
* DIS # F8: 6,8 => CTR => F8: 3
* DIS # H8: 2,7 => CTR => H8: 8
* DIS # I1: 2,7 => CTR => I1: 1,5
* CNT  13 HDP CHAINS /  57 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A9,B4,D2,D5,D8,E2,E8,F4,F7,G5,G9,I7,I8)
* .4..6......5.....99..25....5..18.2.3....75..8...342.....34..65.451...9...6.5.7.34
* PAIR D2: 7,8 BLK 2
D1: 7,8,9                                # reduction candidate for 7,8
D1: 9 => CTR
* .4.96......57....99..25....57.1892.3...675..8...342...78349165.4518.69...6.5.7834
* PAIR D2: 7,8 ROW 2
A2: 7,8,1,2,3,6                          # reduction candidate for 7,8
A2: 7,8 => CTR
* 34..69..5.25....6991625...75.41862.3632975..81..342..6..34..65.4516..9...6.5.7.34
B2: 7,8,1,2,3                            # reduction candidate for 7,8
B2: 7,8                                  # 17 pairs
G2: 7,8,1,3,4                            # reduction candidate for 7,8
G2: 7,8                                  # 13 pairs
H2: 7,8,1,2,4,6                          # reduction candidate for 7,8
H2: 7,8                                  # 22 pairs
* PAIR RESTART
* PAIR D2: 7,8 ROW 2
B2: 7,8,1,2,3                            # reduction candidate for 7,8
B2: 7,8                                  # 17 pairs
G2: 7,8,1,3,4                            # reduction candidate for 7,8
G2: 7,8                                  # 13 pairs
H2: 7,8,1,2,4,6                          # reduction candidate for 7,8
H2: 7,8                                  # 22 pairs
* PAIR E2: 1,3 BLK 2
F2: 1,3,4                                # reduction candidate for 1,3
F2: 1,3                                  # 16 pairs
F3: 1,3,4                                # reduction candidate for 1,3
F3: 1,3                                  # 13 pairs
* PAIR E2: 1,3 ROW 2
A2: 1,3,2,6                              # reduction candidate for 1,3
A2: 1,3 => CTR
* 14..69325325.1..699.625....5.41862.3632975..8...3425.6..34..65.4516..987.6.5.7134
B2: 1,3,2,7,8                            # reduction candidate for 1,3
B2: 1,3                                  # 17 pairs
G2: 1,3,4,7,8                            # reduction candidate for 1,3
G2: 1,3                                  # 18 pairs
* PAIR RESTART
* PAIR E2: 1,3 BLK 2
F2: 1,3,4                                # reduction candidate for 1,3
F2: 1,3                                  # 16 pairs
F3: 1,3,4                                # reduction candidate for 1,3
F3: 1,3                                  # 14 pairs
* PAIR E2: 1,3 ROW 2
B2: 1,3,2,7,8                            # reduction candidate for 1,3
B2: 1,3                                  # 17 pairs
G2: 1,3,4,7,8                            # reduction candidate for 1,3
G2: 1,3                                  # 18 pairs
* PAIR B4: 7,9 BLK 4
C4: 7,9,4                                # reduction candidate for 7,9
C4: 7,9 => CTR
* .4..69...6.5.3...99..25...65..186243..4975168..6342.9...349.6514516..9...6.517834
B6: 7,9,1,8                              # reduction candidate for 7,9
B6: 7,9                                  # 19 pairs
C6: 7,9,6,8                              # reduction candidate for 7,9
C6: 7,9                                  # 17 pairs
* PAIR B4: 7,9 COL B
B7: 7,9,2,8                              # reduction candidate for 7,9
B7: 7,9                                  # 17 pairs
B7: 2,8                                  # 17 pairs
* PAIR G5: 1,4 BLK 6
H5: 1,4,6                                # reduction candidate for 1,4
H5: 6                                    # 22 pairs
H5: 1,4                                  # 18 pairs
* PAIR G5: 1,4 COL G
G2: 1,4,3,7,8                            # reduction candidate for 1,4
G2: 1,4 => CTR
* .4..69.....5.3...99..25....5.41862.3...975..8...342.....349.6514516..9...6.517834
G3: 1,4,3,7,8                            # reduction candidate for 1,4
G3: 1,4 => CTR
* .4..69.....5.3.7.993725..865.41862.33..975..8...3425.77834..6514516..9...6.517834
* PAIR RESTART
* PAIR A9: 2,8 BLK 7
A7: 2,8,7                                # reduction candidate for 2,8
A7: 2,8                                  # 20 pairs
B7: 2,8,7,9                              # reduction candidate for 2,8
B7: 2,8                                  # 17 pairs
C9: 2,8,9                                # reduction candidate for 2,8
C9: 2,8                                  # 15 pairs
* PAIR A9: 2,8 COL A
A1: 2,8,1,3,7                            # reduction candidate for 2,8
A1: 2,8 => CTR
* .4..693156.5....299..25..465.41862.33269754.81..3425..7.34..65.4516..9...6.5.7134
* PAIR RESTART
* PAIR A9: 2,8 BLK 7
A7: 2,8,7                                # reduction candidate for 2,8
A7: 2,8                                  # 20 pairs
B7: 2,8,7,9                              # reduction candidate for 2,8
B7: 2,8                                  # 18 pairs
C9: 2,8,9                                # reduction candidate for 2,8
C9: 2,8                                  # 16 pairs
* PAIR I7: 1,2 ROW 7
E7: 1,2,9                                # reduction candidate for 1,2
E7: 9                                    # 16 pairs
E7: 1,2                                  # 16 pairs
* PAIR I7: 1,2 COL I
I1: 1,2,5,7                              # reduction candidate for 1,2
I1: 1,2                                  # 18 pairs
I1: 5,7                                  # 17 pairs
* PAIR I8: 2,7 BLK 9
H8: 2,7,8                                # reduction candidate for 2,7
H8: 2,7 => CTR
* .4..69.....5.....99..25....5.41862.3...9754.8...342.....34.16524516.89...6.5.7834

* LEVEL 0 PASS 1 ROUND 2 (AUTO SOLVE) (A1,A2,A9,B2,B6,C5,C9,D1,D2,F2,F3,G2,G6,H5,I1,I3)
* .4..69.....5.3...99..25....574186293...9754.8..9342...793418652451623987.6.597134
* PAIR A1: 1,3 BLK 1
B3: 1,3,8                                # reduction candidate for 1,3
B3: 1,3 => SOLVED
* 347869521625731849918254376574186293236975418189342765793418652451623987862597134
* DURATION: 0:00:25.162330  START: 22:07:56.001035  END: 22:08:21.163365 2019-04-30
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060403-absurd-base-pr-001.dot
* REASONING
* DIS # D1: 9 => CTR => D1: 7,8
* DIS D1: 7,8 # A2: 7,8 => CTR => A2: 1,2,3,6
* DIS D1: 7,8 + A2: 1,2,3,6 # A2: 1,3 => CTR => A2: 2,6
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 # C4: 7,9 => CTR => C4: 4
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 # G2: 1,4 => CTR => G2: 3,7,8
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 # G3: 1,4 => CTR => G3: 3,7,8
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 # A1: 2,8 => CTR => A1: 1,3,7
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 # H8: 2,7 => CTR => H8: 8
* PRF D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 + H8: 8 # B3: 1,3 => SOL
* STA D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 + H8: 8 + B3: 1,3
* CNT   9 HDP CHAINS /  40 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Apr&YEAR=2006, 20060403, absurd

Solution

position: 347869521625731849918254376574186293236975418189342765793418652451623987862597134 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 # D1: 7,8 => UNS
* DIS # D1: 9 => CTR => D1: 7,8
* DIS # A2: 7,8 => CTR => A2: 1,2,3,6
* INC # A2: 1,2,3,6 => UNS
* INC # B2: 7,8 => UNS
* INC # G2: 7,8 => UNS
* INC # H2: 7,8 => UNS
* DIS # F1: 1,3 => CTR => F1: 8,9
* INC # F1: 8,9 => UNS
* INC # F2: 1,3 => UNS
* INC # F3: 1,3 => UNS
* DIS # A2: 1,3 => CTR => A2: 2,6,7,8
* INC # A2: 2,6,7,8 => UNS
* INC # B2: 1,3 => UNS
* INC # G2: 1,3 => UNS
* DIS # C4: 7,9 => CTR => C4: 4,6
* INC # C4: 4,6 => UNS
* INC # B6: 7,9 => UNS
* INC # C6: 7,9 => UNS
* INC # H4: 7,9 => UNS
* INC # H4: 4,6 => UNS
* INC # B7: 7,9 => UNS
* INC # B7: 2,8 => UNS
* DIS # C4: 6,9 => CTR => C4: 4,7
* INC # C4: 4,7 => UNS
* INC # H4: 6,9 => UNS
* INC # C5: 6,9 => UNS
* INC # H5: 6,9 => UNS
* INC # H5: 1,4 => UNS
* INC # H5: 6,9 => UNS
* DIS # G2: 1,4 => CTR => G2: 3,7,8
* INC # G2: 3,7,8 => UNS
* DIS # G3: 1,4 => CTR => G3: 3,7,8
* INC # G3: 3,7,8 => UNS
* INC # A7: 2,8 => UNS
* INC # B7: 2,8 => UNS
* INC # C9: 2,8 => UNS
* INC # A1: 2,8 => UNS
* DIS # A2: 2,8 => CTR => A2: 1,3,6,7
* INC # A2: 1,3,6,7 => UNS
* DIS # F1: 1,8 => CTR => F1: 3,9
* INC # F1: 3,9 => UNS
* INC # F2: 1,8 => UNS
* INC # F3: 1,8 => UNS
* DIS # F8: 6,8 => CTR => F8: 3
* INC # F8: 3 => UNS
* INC # E7: 1,2 => UNS
* INC # E7: 9 => UNS
* INC # I1: 1,2 => UNS
* INC # I1: 5,7 => UNS
* DIS # H8: 2,7 => CTR => H8: 8
* INC # H8: 8 => UNS
* DIS # I1: 2,7 => CTR => I1: 1,5
* INC # I1: 1,5 => UNS
* INC # G1: 1,8 => UNS
* INC # G2: 1,8 => UNS
* INC # G3: 1,8 => UNS
* CNT  57 HDP CHAINS /  57 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # D1: 7,8 => UNS
* DIS # D1: 9 => CTR => D1: 7,8
* DIS D1: 7,8 # A2: 7,8 => CTR => A2: 1,2,3,6
* INC D1: 7,8 + A2: 1,2,3,6 # B2: 7,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 # G2: 7,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 # H2: 7,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 # B2: 7,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 # G2: 7,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 # H2: 7,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 # F2: 1,3 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 # F3: 1,3 => UNS
* DIS D1: 7,8 + A2: 1,2,3,6 # A2: 1,3 => CTR => A2: 2,6
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 # B2: 1,3 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 # G2: 1,3 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 # F2: 1,3 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 # F3: 1,3 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 # B2: 1,3 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 # G2: 1,3 => UNS
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 # C4: 7,9 => CTR => C4: 4
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 # B6: 7,9 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 # C6: 7,9 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 # B7: 7,9 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 # B7: 2,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 # H5: 1,4 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 # H5: 6 => UNS
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 # G2: 1,4 => CTR => G2: 3,7,8
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 # G3: 1,4 => CTR => G3: 3,7,8
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 # A7: 2,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 # B7: 2,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 # C9: 2,8 => UNS
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 # A1: 2,8 => CTR => A1: 1,3,7
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 # A7: 2,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 # B7: 2,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 # C9: 2,8 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 # E7: 1,2 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 # E7: 9 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 # I1: 1,2 => UNS
* INC D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 # I1: 5,7 => UNS
* DIS D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 # H8: 2,7 => CTR => H8: 8
* PRF D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 + H8: 8 # B3: 1,3 => SOL
* STA D1: 7,8 + A2: 1,2,3,6 + A2: 2,6 + C4: 4 + G2: 3,7,8 + G3: 3,7,8 + A1: 1,3,7 + H8: 8 + B3: 1,3
* CNT  40 HDP CHAINS /  40 HYP OPENED