Analysis of zz-www.sudokuoftheday.co.uk-20060502-absurd-base.sdk

Contents

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

level: medium

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

position: .2....8..1...86.....95........859..3.....315.7.....9....7435..9.9.2......4.9.7.6. initial

Autosolve

position: .26.9.8..1...86.928.95........859..39....315.7.....9..6.74352.9.9.268....4.917.6. autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # B2: 5 => CTR => B2: 3,7
* DIS # G3: 3,7 => CTR => G3: 4,6
* DIS # H3: 3,7 => CTR => H3: 1,4
* DIS # F3: 1,4 => CTR => F3: 2
* DIS # H1: 1,4 => CTR => H1: 3,7
* DIS # I1: 1,4 => CTR => I1: 5,7
* DIS # F6: 2 => CTR => F6: 1,4
* DIS # D1: 3,7 => CTR => D1: 1
* DIS # G2: 3,7 => CTR => G2: 4,5
* DIS # C4: 2,4 => CTR => C4: 1
* PRF # C4: 1 => SOL
* PRF # C5: 2,4 => SOL
* DIS # C5: 8 => CTR => C5: 2,4
* PRF # H4: 2,4 => SOL
* DIS # H4: 7 => CTR => H4: 2,4
* DIS # B2: 3,5 => CTR => B2: 7
* DIS # C2: 3,5 => CTR => C2: 4
* PRF # C8: 3,5 => SOL
* DIS # C8: 1 => CTR => C8: 3,5
* DIS # C9: 3,5 => CTR => C9: 2,8
* DIS # F6: 2,4 => CTR => F6: 1
* PRF # H6: 2,4 => SOL
* DIS # H6: 8 => CTR => H6: 2,4
* DIS # E3: 2,4 => CTR => E3: 7
* DIS # G4: 4,6 => CTR => G4: 7
* PRF # G4: 7 => SOL
* DIS # I6: 4,6 => CTR => I6: 8
* PRF # I6: 8 => SOL
* PRF # I3: 4,6 => SOL
* DIS # I3: 1,7 => CTR => I3: 4,6
* PRF # C8: 3,5 => SOL
* DIS # C8: 1 => CTR => C8: 3,5
* DIS # A9: 3,5 => CTR => A9: 2
* DIS # C9: 3,5 => CTR => C9: 2,8
* DIS # G8: 3,5 => CTR => G8: 4,7
* DIS # A1: 4 => CTR => A1: 3,5
* DIS # G8: 3,5 => CTR => G8: 4,7
* DIS # A9: 3,5 => CTR => A9: 2
* DIS # C9: 3,5 => CTR => C9: 2,8
* DIS # G2: 4,7 => CTR => G2: 3,5
* DIS # C9: 2,3 => CTR => C9: 5,8
* CNT  41 HDP CHAINS /  66 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 # B2: 5 => CTR => B2: 3,7
* DIS B2: 3,7 # G3: 3,7 => CTR => G3: 4,6
* DIS B2: 3,7 + G3: 4,6 # H3: 3,7 => CTR => H3: 1,4
* DIS B2: 3,7 + G3: 4,6 + H3: 1,4 # F3: 1,4 => CTR => F3: 2
* DIS B2: 3,7 + G3: 4,6 + H3: 1,4 + F3: 2 # C4: 2,4 => CTR => C4: 1
* PRF B2: 3,7 + G3: 4,6 + H3: 1,4 + F3: 2 + C4: 1 => SOL
* STA B2: 3,7 + G3: 4,6 + H3: 1,4 + F3: 2 + C4: 1
* CNT   6 HDP CHAINS /   6 HYP OPENED

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

Details

Positions

.2....8..1...86.....95........859..3.....315.7.....9....7435..9.9.2......4.9.7.6. initial
.26.9.8..1...86.928.95........859..39....315.7.....9..6.74352.9.9.268....4.917.6. autosolve
526194837174386592839572614461859723982743156753621948617435289395268471248917365 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (17)
B3: 3,7
F1: 1,4
D2: 3,7
A4: 2,4
B4: 1,6
B5: 6,8
B6: 3,5
C6: 3,5
D5: 6,7
D6: 1,6
E6: 2,4
I5: 4,6
B7: 1,8
A8: 3,5
H7: 1,8
G9: 3,5
I9: 5,8

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
B4,C4: 1.. / B4 = 1  =>  0 pairs (X) / C4 = 1  =>  0 pairs (_)
D6,F6: 1.. / D6 = 1  =>  0 pairs (X) / F6 = 1  => 18 pairs (_)
B7,C8: 1.. / B7 = 1  =>  0 pairs (*) / C8 = 1  =>  0 pairs (X)
B7,H7: 1.. / B7 = 1  =>  0 pairs (*) / H7 = 1  =>  0 pairs (X)
B4,B7: 1.. / B4 = 1  =>  0 pairs (X) / B7 = 1  =>  0 pairs (_)
C4,C8: 1.. / C4 = 1  =>  0 pairs (*) / C8 = 1  =>  0 pairs (X)
D1,D6: 1.. / D1 = 1  => 18 pairs (_) / D6 = 1  =>  0 pairs (X)
E3,F3: 2.. / E3 = 2  =>  0 pairs (X) / F3 = 2  => 19 pairs (_)
H4,H6: 2.. / H4 = 2  =>  0 pairs (*) / H6 = 2  =>  0 pairs (X)
A9,C9: 2.. / A9 = 2  => 21 pairs (_) / C9 = 2  =>  0 pairs (X)
C5,E5: 2.. / C5 = 2  =>  0 pairs (*) / E5 = 2  =>  0 pairs (X)
A4,A9: 2.. / A4 = 2  =>  0 pairs (X) / A9 = 2  => 21 pairs (_)
F3,F6: 2.. / F3 = 2  => 19 pairs (_) / F6 = 2  =>  0 pairs (X)
D1,D2: 3.. / D1 = 3  =>  0 pairs (X) / D2 = 3  => 19 pairs (_)
B6,C6: 3.. / B6 = 3  =>  0 pairs (X) / C6 = 3  => 20 pairs (_)
A1,C2: 4.. / A1 = 4  =>  0 pairs (X) / C2 = 4  => 21 pairs (_)
C2,G2: 4.. / C2 = 4  => 21 pairs (_) / G2 = 4  =>  0 pairs (X)
A1,A4: 4.. / A1 = 4  =>  0 pairs (X) / A4 = 4  => 21 pairs (_)
I1,G2: 5.. / I1 = 5  =>  0 pairs (X) / G2 = 5  => 20 pairs (_)
B6,C6: 5.. / B6 = 5  => 20 pairs (_) / C6 = 5  =>  0 pairs (X)
A1,I1: 5.. / A1 = 5  => 20 pairs (_) / I1 = 5  =>  0 pairs (X)
B2,B6: 5.. / B2 = 5  =>  0 pairs (X) / B6 = 5  => 20 pairs (_)
G3,I3: 6.. / G3 = 6  =>  0 pairs (*) / I3 = 6  =>  0 pairs (X)
B4,B5: 6.. / B4 = 6  =>  0 pairs (*) / B5 = 6  =>  0 pairs (X)
D5,D6: 6.. / D5 = 6  =>  0 pairs (X) / D6 = 6  => 18 pairs (_)
B4,G4: 6.. / B4 = 6  =>  0 pairs (*) / G4 = 6  =>  0 pairs (X)
D6,I6: 6.. / D6 = 6  => 18 pairs (_) / I6 = 6  =>  0 pairs (X)
G3,G4: 6.. / G3 = 6  =>  0 pairs (*) / G4 = 6  =>  0 pairs (X)
B2,B3: 7.. / B2 = 7  => 18 pairs (_) / B3 = 7  =>  0 pairs (X)
D5,E5: 7.. / D5 = 7  => 18 pairs (_) / E5 = 7  =>  0 pairs (X)
G4,H4: 7.. / G4 = 7  =>  0 pairs (*) / H4 = 7  =>  0 pairs (X)
E3,E5: 7.. / E3 = 7  => 18 pairs (_) / E5 = 7  =>  0 pairs (X)
B5,C5: 8.. / B5 = 8  =>  0 pairs (*) / C5 = 8  =>  0 pairs (X)
H6,I6: 8.. / H6 = 8  =>  0 pairs (X) / I6 = 8  =>  0 pairs (_)
B7,C9: 8.. / B7 = 8  =>  0 pairs (X) / C9 = 8  =>  0 pairs (_)
H7,I9: 8.. / H7 = 8  =>  0 pairs (*) / I9 = 8  =>  0 pairs (X)
B7,H7: 8.. / B7 = 8  =>  0 pairs (X) / H7 = 8  =>  0 pairs (_)
C9,I9: 8.. / C9 = 8  =>  0 pairs (*) / I9 = 8  =>  0 pairs (X)
B5,B7: 8.. / B5 = 8  =>  0 pairs (*) / B7 = 8  =>  0 pairs (X)
C5,C9: 8.. / C5 = 8  =>  0 pairs (X) / C9 = 8  =>  0 pairs (_)
H6,H7: 8.. / H6 = 8  =>  0 pairs (X) / H7 = 8  =>  0 pairs (_)
I6,I9: 8.. / I6 = 8  =>  0 pairs (*) / I9 = 8  =>  0 pairs (X)
* DURATION: 0:00:47.219919  START: 22:49:24.133081  END: 22:50:11.353000 2019-04-30
* CP COUNT: (42)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A4,A8,B3,B4,B5,B6,B7,C6,D2,D5,D6,E6,F1,G9,H7,I5,I9)
* .26.9.8..1...86.928.95........859..39....315.7.....9..6.74352.9.9.268....4.917.6.
* PAIR B3: 3,7 BLK 1
B2: 3,7,5                                # reduction candidate for 3,7
B2: 5 => CTR
* .26.9.8.515..86.928795........859..39.26731547351..9.66.74352.9.9.268..7248917.6.
B2: 3,7                                  # 20 pairs
* PAIR B3: 3,7 ROW 3
G3: 3,7,4,6                              # reduction candidate for 3,7
G3: 3,7 => CTR
* .26.9.8..1...86.928.95....6...8596739687231547..641928687435219.91268....4.917.65
G3: 4,6                                  # 18 pairs
H3: 3,7,1,4                              # reduction candidate for 3,7
H3: 3,7 => CTR
* 526.9.8..1.4.865928.95.....4.1859.2398267315475....9..6.74352.9.9.268...248917365
H3: 1,4                                  # 18 pairs
* PAIR F1: 1,4 BLK 2
F3: 1,4,2                                # reduction candidate for 1,4
F3: 1,4 => CTR
* .26.9.8..1...86.928.952.......859..39.2.731547...42986687435219.91268...24.917.68
F3: 2                                    # 19 pairs
* PAIR F1: 1,4 ROW 1
H1: 1,4,3,7                              # reduction candidate for 1,4
H1: 1,4 => CTR
* .26.9.8..1.4.86.928.95.....4..859..39..6731547..1..9.66.74352.9.9.268...24.917.68
H1: 3,7                                  # 18 pairs
I1: 1,4,5,7                              # reduction candidate for 1,4
I1: 1,4 => CTR
* 526.9.8..1.4.865928.95.....4..859..39..6731547531..9.66.74352.939.268...24.917368
I1: 5,7                                  # 18 pairs
* PAIR F1: 1,4 COL F
F6: 1,4,2                                # reduction candidate for 1,4
F6: 2 => CTR
* .26.9.8..1...86.928.95........859..39....315.7..1.29.66.74352.9.9.268....4.917.68
F6: 1,4                                  # 19 pairs
* PAIR D2: 3,7 BLK 2
D1: 3,7,1                                # reduction candidate for 3,7
D1: 3,7 => CTR
* .26.9.8..1...86.928.95..6...61859..398...315.7..1..9.66.74352.9.9.268....4.917.68
D1: 1                                    # 18 pairs
* PAIR D2: 3,7 ROW 2
B2: 3,7,5                                # reduction candidate for 3,7
B2: 3,7                                  # 20 pairs
G2: 3,7,4,5                              # reduction candidate for 3,7
G2: 3,7 => CTR
* 326.9.8.51543867928795.....4..8596739687.315.7.....9..6.74352.9.9.268...24.917.68
G2: 4,5                                  # 18 pairs
* PAIR A4: 2,4 BLK 4
C4: 2,4,1                                # reduction candidate for 2,4
C4: 2,4 => CTR
* .26.9.8..1...86.928.95......1.8596739687231547..6419286874352.9.9.268....4.917.6.
C4: 1 => SOLVED
* 526194837174386592839572614461859723982743156753621948617435289395268471248917365
C5: 2,4,8                                # reduction candidate for 2,4
C5: 2,4 => SOLVED
* 526194837174386592839572614461859723982743156753621948617435289395268471248917365
C5: 8 => CTR
* .26.9.8..1...86.928.95........859..39.8.231547...41928687435219.91268....4.917.65
* PAIR A4: 2,4 ROW 4
H4: 2,4,7                                # reduction candidate for 2,4
H4: 2,4 => SOLVED
* 526194837174386592839572614461859723982743156753621948617435289395268471248917365
H4: 7 => CTR
* 526.9.8..1.4.865928.95.2...4.2859.739....315.7.....9286.7435289.9.268....48917.65
* PAIR B6: 3,5 COL B
B2: 3,5,7                                # reduction candidate for 3,5
B2: 3,5 => CTR
* .26.9.8..1...86.928795........859..39.26731547..1..9.66.74352.9.9.268...248917365
B2: 7                                    # 18 pairs
* PAIR C6: 3,5 COL C
C2: 3,5,4                                # reduction candidate for 3,5
C2: 3,5 => CTR
* 426.918.51...864928.95.....2..859..39...2315.7..14.9..6.74352.9.9.268....4.917.6.
C2: 4                                    # 21 pairs
C8: 3,5,1                                # reduction candidate for 3,5
C8: 3,5 => SOLVED
* 526194837174386592839572614461859723982743156753621948617435289395268471248917365
C8: 1 => CTR
* .26.9.8..1...86.928.95......1.8596739687231547..6419286874352.9.91268....4.917.6.
C9: 3,5,2,8                              # reduction candidate for 3,5
C9: 3,5 => CTR
* .26.9.8..1...86.928.95........859..39.8.231547...41928687435219.91268...24.917.65
C9: 2,8                                  # 18 pairs
* PAIR E6: 2,4 BLK 5
E5: 2,4,7                                # reduction candidate for 2,4
E5: 2,4                                  # 18 pairs
F6: 2,4,1                                # reduction candidate for 2,4
F6: 2,4 => CTR
* .26.9.8..1...86.928.95..6...61859..398...315.7..1..9.66.74352.9.9.268....4.917.68
F6: 1                                    # 18 pairs
* PAIR E6: 2,4 ROW 6
H6: 2,4,8                                # reduction candidate for 2,4
H6: 2,4 => SOLVED
* 526194837174386592839572614461859723982743156753621948617435289395268471248917365
H6: 8 => CTR
* .26.9.8..1...86.928.95........859.239.2..315.7.....98.687435219.91268...24.917.68
* PAIR E6: 2,4 COL E
E3: 2,4,7                                # reduction candidate for 2,4
E3: 2,4 => CTR
* .26.9.8..1...86.928.95........859..39.26731547..1..9.66.74352.9.9.268...248917365
E3: 7                                    # 18 pairs
* PAIR I5: 4,6 BLK 6
G4: 4,6,7                                # reduction candidate for 4,6
G4: 4,6 => CTR
* 526.9.8..1.4.865928.95.2...4.2859.739....315.7.....9286.7435289.9.268....48917.65
G4: 7 => SOLVED
* 526194837174386592839572614461859723982743156753621948617435289395268471248917365
I6: 4,6,8                                # reduction candidate for 4,6
I6: 4,6 => CTR
* .26.9.8..1...86.928.95......1.8596.39....315.7.....98.687435219.91268....4.917.68
I6: 8 => SOLVED
* 526194837174386592839572614461859723982743156753621948617435289395268471248917365
* PAIR I5: 4,6 COL I
I3: 4,6,1,7                              # reduction candidate for 4,6
I3: 4,6 => SOLVED
* 526194837174386592839572614461859723982743156753621948617435289395268471248917365
I3: 1,7 => CTR
* 526.9.8.41.4.865928.95.46..461859723982.4315675362.9486174352893952684..248917365
* PAIR A8: 3,5 BLK 7
C8: 3,5,1                                # reduction candidate for 3,5
C8: 3,5 => SOLVED
* 526194837174386592839572614461859723982743156753621948617435289395268471248917365
C8: 1 => CTR
* .26.9.8..1...86.928.95......1.8596739687231547..6419286874352.9.91268....4.917.6.
A9: 3,5,2                                # reduction candidate for 3,5
A9: 3,5 => CTR
* .26.9.8..1...86.928.95.....2..859..39...2315.7...419286.7435289.9.268....4.917.6.
A9: 2                                    # 21 pairs
C9: 3,5,2,8                              # reduction candidate for 3,5
C9: 3,5 => CTR
* .26.9.8..1...86.928.95........859..39.8.231547...41928687435219.91268...24.917.65
C9: 2,8                                  # 18 pairs
* PAIR A8: 3,5 ROW 8
G8: 3,5,4,7                              # reduction candidate for 3,5
G8: 3,5 => CTR
* .26.9.8.51...86.928.95..6.1...859..39....315.7.....98.687435219.91268..7.4.917.68
G8: 4,7                                  # 18 pairs
* PAIR A8: 3,5 COL A
A1: 3,5,4                                # reduction candidate for 3,5
A1: 4 => CTR
* 426.918.51...864928.95.....2..859..39...2315.7..14.9..6.74352.9.9.268....4.917.6.
A1: 3,5                                  # 21 pairs
* PAIR G9: 3,5 BLK 9
G8: 3,5,4,7                              # reduction candidate for 3,5
G8: 3,5 => CTR
* .26.9.8.51...86.928.95..6.1...859..39....315.7.....98.687435219.91268..7.4.917.68
G8: 4,7                                  # 18 pairs
* PAIR G9: 3,5 ROW 9
A9: 3,5,2                                # reduction candidate for 3,5
A9: 3,5 => CTR
* .26.9.8..1...86.928.95.....2..859..39...2315.7...419286.7435289.9.268....4.917.6.
A9: 2                                    # 21 pairs
C9: 3,5,2,8                              # reduction candidate for 3,5
C9: 3,5 => CTR
* .26.9.8..1...86.928.95........859..39.8.231547...41928687435219.91268...24.917.65
C9: 2,8                                  # 18 pairs
* PAIR G9: 3,5 COL G
G2: 3,5,4,7                              # reduction candidate for 3,5
G2: 4,7 => CTR
* .26.9.8.51...86.928.95........859..39.8.231547.....9..6.74352.9.9.268....4.917.68
G2: 3,5                                  # 23 pairs
* PAIR I9: 5,8 ROW 9
C9: 5,8,2,3                              # reduction candidate for 5,8
C9: 2,3 => CTR
* .26.9.8..1...86.928.95........859..39.8.231547...41928687435219.91268....4.917.65
C9: 5,8                                  # 22 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060502-absurd-base-pr-000.dot
* REASONING
* DIS # B2: 5 => CTR => B2: 3,7
* DIS # G3: 3,7 => CTR => G3: 4,6
* DIS # H3: 3,7 => CTR => H3: 1,4
* DIS # F3: 1,4 => CTR => F3: 2
* DIS # H1: 1,4 => CTR => H1: 3,7
* DIS # I1: 1,4 => CTR => I1: 5,7
* DIS # F6: 2 => CTR => F6: 1,4
* DIS # D1: 3,7 => CTR => D1: 1
* DIS # G2: 3,7 => CTR => G2: 4,5
* DIS # C4: 2,4 => CTR => C4: 1
* PRF # C4: 1 => SOL
* PRF # C5: 2,4 => SOL
* DIS # C5: 8 => CTR => C5: 2,4
* PRF # H4: 2,4 => SOL
* DIS # H4: 7 => CTR => H4: 2,4
* DIS # B2: 3,5 => CTR => B2: 7
* DIS # C2: 3,5 => CTR => C2: 4
* PRF # C8: 3,5 => SOL
* DIS # C8: 1 => CTR => C8: 3,5
* DIS # C9: 3,5 => CTR => C9: 2,8
* DIS # F6: 2,4 => CTR => F6: 1
* PRF # H6: 2,4 => SOL
* DIS # H6: 8 => CTR => H6: 2,4
* DIS # E3: 2,4 => CTR => E3: 7
* DIS # G4: 4,6 => CTR => G4: 7
* PRF # G4: 7 => SOL
* DIS # I6: 4,6 => CTR => I6: 8
* PRF # I6: 8 => SOL
* PRF # I3: 4,6 => SOL
* DIS # I3: 1,7 => CTR => I3: 4,6
* PRF # C8: 3,5 => SOL
* DIS # C8: 1 => CTR => C8: 3,5
* DIS # A9: 3,5 => CTR => A9: 2
* DIS # C9: 3,5 => CTR => C9: 2,8
* DIS # G8: 3,5 => CTR => G8: 4,7
* DIS # A1: 4 => CTR => A1: 3,5
* DIS # G8: 3,5 => CTR => G8: 4,7
* DIS # A9: 3,5 => CTR => A9: 2
* DIS # C9: 3,5 => CTR => C9: 2,8
* DIS # G2: 4,7 => CTR => G2: 3,5
* DIS # C9: 2,3 => CTR => C9: 5,8
* CNT  41 HDP CHAINS /  66 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A4,A8,B3,B4,B5,B6,B7,C6,D2,D5,D6,E6,F1,G9,H7,I5,I9)
* .26.9.8..1...86.928.95........859..39....315.7.....9..6.74352.9.9.268....4.917.6.
* PAIR B3: 3,7 BLK 1
B2: 3,7,5                                # reduction candidate for 3,7
B2: 5 => CTR
* .26.9.8.515..86.928795........859..39.26731547351..9.66.74352.9.9.268..7248917.6.
* PAIR B3: 3,7 ROW 3
G3: 3,7,4,6                              # reduction candidate for 3,7
G3: 3,7 => CTR
* .26.9.8..1...86.928.95....6...859673968723154753641928687435219.91268....4.917.65
H3: 3,7,1,4                              # reduction candidate for 3,7
H3: 3,7 => CTR
* 526.9.8..1.4.865928.95.....4.1859.239826731547531..9..6.74352.9.9.268...248917365
* PAIR RESTART
* PAIR F1: 1,4 BLK 2
F3: 1,4,2                                # reduction candidate for 1,4
F3: 1,4 => CTR
* .26.9.83.17.386.9283952...7...859..39.2.73154753.42986687435219.91268..5245917368
* PAIR A4: 2,4 BLK 4
C4: 2,4,1                                # reduction candidate for 2,4
C4: 2,4 => CTR
* .26.9.83.17.386.928395.2....1.8596739687231547536419286874352.9.9.268....4.917.6.
C4: 1 => SOLVED
* 526194837174386592839572614461859723982743156753621948617435289395268471248917365
* DURATION: 0:00:05.921426  START: 22:50:53.653848  END: 22:50:59.575274 2019-04-30
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060502-absurd-base-pr-001.dot
* REASONING
* DIS # B2: 5 => CTR => B2: 3,7
* DIS B2: 3,7 # G3: 3,7 => CTR => G3: 4,6
* DIS B2: 3,7 + G3: 4,6 # H3: 3,7 => CTR => H3: 1,4
* DIS B2: 3,7 + G3: 4,6 + H3: 1,4 # F3: 1,4 => CTR => F3: 2
* DIS B2: 3,7 + G3: 4,6 + H3: 1,4 + F3: 2 # C4: 2,4 => CTR => C4: 1
* PRF B2: 3,7 + G3: 4,6 + H3: 1,4 + F3: 2 + C4: 1 => SOL
* STA B2: 3,7 + G3: 4,6 + H3: 1,4 + F3: 2 + C4: 1
* CNT   6 HDP CHAINS /   6 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=May&YEAR=2006, 20060502, absurd

Solution

position: 526194837174386592839572614461859723982743156753621948617435289395268471248917365 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 # B2: 3,7 => UNS
* DIS # B2: 5 => CTR => B2: 3,7
* DIS # G3: 3,7 => CTR => G3: 4,6
* INC # G3: 4,6 => UNS
* DIS # H3: 3,7 => CTR => H3: 1,4
* INC # H3: 1,4 => UNS
* DIS # F3: 1,4 => CTR => F3: 2
* INC # F3: 2 => UNS
* DIS # H1: 1,4 => CTR => H1: 3,7
* INC # H1: 3,7 => UNS
* DIS # I1: 1,4 => CTR => I1: 5,7
* INC # I1: 5,7 => UNS
* INC # F6: 1,4 => UNS
* DIS # F6: 2 => CTR => F6: 1,4
* DIS # D1: 3,7 => CTR => D1: 1
* INC # D1: 1 => UNS
* INC # B2: 3,7 => UNS
* DIS # G2: 3,7 => CTR => G2: 4,5
* INC # G2: 4,5 => UNS
* DIS # C4: 2,4 => CTR => C4: 1
* PRF # C4: 1 => SOL
* PRF # C5: 2,4 => SOL
* DIS # C5: 8 => CTR => C5: 2,4
* PRF # H4: 2,4 => SOL
* DIS # H4: 7 => CTR => H4: 2,4
* DIS # B2: 3,5 => CTR => B2: 7
* INC # B2: 7 => UNS
* DIS # C2: 3,5 => CTR => C2: 4
* INC # C2: 4 => UNS
* PRF # C8: 3,5 => SOL
* DIS # C8: 1 => CTR => C8: 3,5
* DIS # C9: 3,5 => CTR => C9: 2,8
* INC # C9: 2,8 => UNS
* INC # E5: 2,4 => UNS
* DIS # F6: 2,4 => CTR => F6: 1
* INC # F6: 1 => UNS
* PRF # H6: 2,4 => SOL
* DIS # H6: 8 => CTR => H6: 2,4
* DIS # E3: 2,4 => CTR => E3: 7
* INC # E3: 7 => UNS
* DIS # G4: 4,6 => CTR => G4: 7
* PRF # G4: 7 => SOL
* DIS # I6: 4,6 => CTR => I6: 8
* PRF # I6: 8 => SOL
* PRF # I3: 4,6 => SOL
* DIS # I3: 1,7 => CTR => I3: 4,6
* PRF # C8: 3,5 => SOL
* DIS # C8: 1 => CTR => C8: 3,5
* DIS # A9: 3,5 => CTR => A9: 2
* INC # A9: 2 => UNS
* DIS # C9: 3,5 => CTR => C9: 2,8
* INC # C9: 2,8 => UNS
* DIS # G8: 3,5 => CTR => G8: 4,7
* INC # G8: 4,7 => UNS
* INC # A1: 3,5 => UNS
* DIS # A1: 4 => CTR => A1: 3,5
* DIS # G8: 3,5 => CTR => G8: 4,7
* INC # G8: 4,7 => UNS
* DIS # A9: 3,5 => CTR => A9: 2
* INC # A9: 2 => UNS
* DIS # C9: 3,5 => CTR => C9: 2,8
* INC # C9: 2,8 => UNS
* INC # G2: 3,5 => UNS
* DIS # G2: 4,7 => CTR => G2: 3,5
* INC # C9: 5,8 => UNS
* DIS # C9: 2,3 => CTR => C9: 5,8
* CNT  66 HDP CHAINS /  66 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # B2: 3,7 => UNS
* DIS # B2: 5 => CTR => B2: 3,7
* DIS B2: 3,7 # G3: 3,7 => CTR => G3: 4,6
* DIS B2: 3,7 + G3: 4,6 # H3: 3,7 => CTR => H3: 1,4
* DIS B2: 3,7 + G3: 4,6 + H3: 1,4 # F3: 1,4 => CTR => F3: 2
* DIS B2: 3,7 + G3: 4,6 + H3: 1,4 + F3: 2 # C4: 2,4 => CTR => C4: 1
* PRF B2: 3,7 + G3: 4,6 + H3: 1,4 + F3: 2 + C4: 1 => SOL
* STA B2: 3,7 + G3: 4,6 + H3: 1,4 + F3: 2 + C4: 1
* CNT   7 HDP CHAINS /   6 HYP OPENED