Analysis of zz-www.sudokuoftheday.co.uk-20190309-absurd-base.sdk

Contents

Sudoku from http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Mar&YEAR=2019

level: medium

Sudoku from http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Mar&YEAR=2019

position: .........8.6....237....51.61......9..2..3...1..792...4...5..7..9..6......34.....8 initial

Autosolve

position: ....6....8.6....237....51.61...5..9..29.3...1..7921..4...5..7..97.6......34.....8 autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # B2: 4,9 => CTR => B2: 1,5
* PRF # E3: 8 => SOL
* DIS # C1: 2,3 => CTR => C1: 1,5
* DIS # H1: 4,8 => CTR => H1: 5,7
* DIS # G4: 3,8 => CTR => G4: 2,6
* DIS # A9: 5 => CTR => A9: 2,6
* DIS # G9: 2,9 => CTR => G9: 5,6
* DIS # F7: 2,9 => CTR => F7: 3,4,8
* DIS # G8: 2,5 => CTR => G8: 3,4
* DIS # C8: 1,8 => CTR => C8: 2,5
* CNT  10 HDP CHAINS /  28 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: 4,9 => CTR => B2: 1,5
* DIS B2: 1,5 # B1: 1,5 => CTR => B1: 4,9
* DIS B2: 1,5 + B1: 4,9 # E3: 4,9 => CTR => E3: 8
* PRF B2: 1,5 + B1: 4,9 + E3: 8 => SOL
* STA B2: 1,5 + B1: 4,9 + E3: 8
* CNT   4 HDP CHAINS /   5 HYP OPENED

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

Details

Positions

.........8.6....237....51.61......9..2..3...1..792...4...5..7..9..6......34.....8 initial
....6....8.6....237....51.61...5..9..29.3...1..7921..4...5..7..97.6......34.....8 autosolve
341269875856174923792385146183456297429837651567921384218543769975618432634792518 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (9)
B3: 4,9
C3: 2,3
D3: 2,3
H3: 4,8
C4: 3,8
I4: 2,7
A7: 2,6
I7: 2,9
I8: 2,5

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
G4,I4: 2.. / G4 = 2  => 13 pairs (_) / I4 = 2  =>  0 pairs (X)
C3,D3: 2.. / C3 = 2  =>  8 pairs (_) / D3 = 2  =>  0 pairs (X)
D1,D3: 3.. / D1 = 3  =>  0 pairs (X) / D3 = 3  =>  8 pairs (_)
C4,A6: 3.. / C4 = 3  => 12 pairs (_) / A6 = 3  =>  0 pairs (X)
F7,F8: 3.. / F7 = 3  =>  9 pairs (_) / F8 = 3  => 11 pairs (_)
C3,D3: 3.. / C3 = 3  =>  0 pairs (X) / D3 = 3  =>  8 pairs (_)
C4,G4: 3.. / C4 = 3  => 12 pairs (_) / G4 = 3  =>  0 pairs (X)
F7,H7: 3.. / F7 = 3  =>  9 pairs (_) / H7 = 3  => 11 pairs (_)
A1,A6: 3.. / A1 = 3  => 12 pairs (_) / A6 = 3  =>  0 pairs (X)
B4,A5: 4.. / B4 = 4  =>  0 pairs (X) / A5 = 4  => 11 pairs (_)
A1,A5: 4.. / A1 = 4  =>  0 pairs (X) / A5 = 4  => 11 pairs (_)
C8,A9: 5.. / C8 = 5  => 17 pairs (_) / A9 = 5  =>  0 pairs (X)
B2,G2: 5.. / B2 = 5  => 17 pairs (_) / G2 = 5  =>  0 pairs (X)
C1,C8: 5.. / C1 = 5  =>  0 pairs (X) / C8 = 5  => 17 pairs (_)
I1,I8: 5.. / I1 = 5  => 17 pairs (_) / I8 = 5  =>  0 pairs (X)
F4,F5: 6.. / F4 = 6  => 10 pairs (_) / F5 = 6  => 11 pairs (_)
H1,I1: 7.. / H1 = 7  => 13 pairs (_) / I1 = 7  =>  0 pairs (X)
I4,H5: 7.. / I4 = 7  => 13 pairs (_) / H5 = 7  =>  0 pairs (X)
E2,E9: 7.. / E2 = 7  => 13 pairs (_) / E9 = 7  => 11 pairs (_)
H1,H5: 7.. / H1 = 7  => 13 pairs (_) / H5 = 7  =>  0 pairs (X)
I1,I4: 7.. / I1 = 7  =>  0 pairs (X) / I4 = 7  => 13 pairs (_)
E3,H3: 8.. / E3 = 8  =>  0 pairs (*) / H3 = 8  =>  0 pairs (X)
I7,G9: 9.. / I7 = 9  =>  9 pairs (_) / G9 = 9  =>  0 pairs (X)
B3,E3: 9.. / B3 = 9  =>  9 pairs (_) / E3 = 9  => 15 pairs (_)
I1,I7: 9.. / I1 = 9  =>  0 pairs (X) / I7 = 9  =>  9 pairs (_)
* DURATION: 0:00:26.212300  START: 04:22:20.208717  END: 04:22:46.421017 2019-05-01
* CP COUNT: (25)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A7,B3,C3,C4,D3,H3,I4,I7,I8)
* ....6....8.6....237....51.61...5..9..29.3...1..7921..4...5..7..97.6......34.....8
* PAIR B3: 4,9 BLK 1
B1: 4,9,1,5                              # reduction candidate for 4,9
B1: 4,9                                  # 13 pairs
B2: 4,9,1,5                              # reduction candidate for 4,9
B2: 4,9 => CTR
* 21536..798.6...5237.32.51.61.8.5..97.29.3..51.57921..4...5..7.29726....5534...968
B2: 1,5                                  # 10 pairs
* PAIR B3: 4,9 ROW 3
E3: 4,9,8                                # reduction candidate for 4,9
E3: 8 => SOLVED
* 341269875856174923792385146183456297429837651567921384218543769975618432634792518
E3: 4,9                                  # 10 pairs
* PAIR C3: 2,3 BLK 1
A1: 2,3,4,5                              # reduction candidate for 2,3
A1: 2,3                                  # 13 pairs
C1: 2,3,1,5                              # reduction candidate for 2,3
C1: 2,3 => CTR
* ....6...5856....237....51.61...5.297.29.3...1..7921..4..15..7.99756....2.34.....8
C1: 1,5                                  # 13 pairs
* PAIR D3: 2,3 BLK 2
D1: 2,3,1,4,8                            # reduction candidate for 2,3
D1: 2,3                                  # 11 pairs
D1: 1,4,8                                # 11 pairs
* PAIR H3: 4,8 BLK 3
G1: 4,8,5,9                              # reduction candidate for 4,8
G1: 4,8                                  # 12 pairs
H1: 4,8,5,7                              # reduction candidate for 4,8
H1: 4,8 => CTR
* ..5.6...78.6...5237....51.61...5..92.29.3..71.57921..4...5..7.997.6....5534.....8
H1: 5,7                                  # 10 pairs
* PAIR H3: 4,8 ROW 3
E3: 4,8,9                                # reduction candidate for 4,8
E3: 9                                    # 15 pairs
E3: 4,8                                  #  9 pairs
* PAIR C4: 3,8 ROW 4
G4: 3,8,2,6                              # reduction candidate for 3,8
G4: 3,8 => CTR
* ..5.6...78.6...5237....51.61...5..92.29.3..71.57921..4...5..7.997.6....5534.....8
G4: 2,6                                  # 13 pairs
* PAIR A7: 2,6 BLK 7
A9: 2,6,5                                # reduction candidate for 2,6
A9: 5 => CTR
* 2.536..798.6...5237.32.51.61.8.5..97.29.3..51.57921..4...5..7.29726....5534...968
A9: 2,6                                  # 17 pairs
* PAIR I7: 2,9 BLK 9
G9: 2,9,5,6                              # reduction candidate for 2,9
G9: 2,9 => CTR
* 2.536..798.6...5237.32.51.61.8.5..97.29.3..51.57921..4...5..7.29726....5534...968
G9: 5,6                                  # 10 pairs
* PAIR I7: 2,9 ROW 7
F7: 2,9,3,4,8                            # reduction candidate for 2,9
F7: 2,9 => CTR
* ....6..4.8.6....2374..951861...5..9.429.3...1..7921.646..54.73.97.683.1..34...658
F7: 3,4,8                                #  9 pairs
* PAIR I8: 2,5 BLK 9
G8: 2,5,3,4                              # reduction candidate for 2,5
G8: 2,5 => CTR
* ..5.6..798.6....237....51861...5..9..29.3...1..7921..4...5..7..97.6......34.....8
G8: 3,4                                  # 10 pairs
G9: 2,5,6,9                              # reduction candidate for 2,5
G9: 2,5                                  # 12 pairs
* PAIR I8: 2,5 ROW 8
C8: 2,5,1,8                              # reduction candidate for 2,5
C8: 1,8 => CTR
* ..5.6..798.6...5237....51.61...5..97.29.3..51.57921..4...5..7.297.6.2..5534...968
C8: 2,5                                  # 16 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20190309-absurd-base-pr-000.dot
* REASONING
* DIS # B2: 4,9 => CTR => B2: 1,5
* PRF # E3: 8 => SOL
* DIS # C1: 2,3 => CTR => C1: 1,5
* DIS # H1: 4,8 => CTR => H1: 5,7
* DIS # G4: 3,8 => CTR => G4: 2,6
* DIS # A9: 5 => CTR => A9: 2,6
* DIS # G9: 2,9 => CTR => G9: 5,6
* DIS # F7: 2,9 => CTR => F7: 3,4,8
* DIS # G8: 2,5 => CTR => G8: 3,4
* DIS # C8: 1,8 => CTR => C8: 2,5
* CNT  10 HDP CHAINS /  28 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A7,B3,C3,C4,D3,H3,I4,I7,I8)
* ....6....8.6....237....51.61...5..9..29.3...1..7921..4...5..7..97.6......34.....8
* PAIR B3: 4,9 BLK 1
B1: 4,9,1,5                              # reduction candidate for 4,9
B1: 4,9                                  # 13 pairs
B2: 4,9,1,5                              # reduction candidate for 4,9
B2: 4,9 => CTR
* 21536..798.6...5237.32.51.61.8.5..97.29.3..51.57921..4...5..7.29726....5534...968
* RESTART
* PAIR B3: 4,9 BLK 1
B1: 4,9,1,5                              # reduction candidate for 4,9
B1: 1,5 => CTR
* 4...6....8.6....2379...51.6148756392.29.3..713.7921..4.8.5..7.997.6....5534.....8
* PAIR B3: 4,9 ROW 3
E3: 4,9,8                                # reduction candidate for 4,9
E3: 4,9 => CTR
* 3.1.6..75856....237.23.51861.3.5.297429.3...15.7921..4.1854.7.9975683412.34.....8
E3: 8 => SOLVED
* 341269875856174923792385146183456297429837651567921384218543769975618432634792518
* DURATION: 0:00:05.556324  START: 04:23:03.805258  END: 04:23:09.361582 2019-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20190309-absurd-base-pr-001.dot
* REASONING
* DIS # B2: 4,9 => CTR => B2: 1,5
* DIS B2: 1,5 # B1: 1,5 => CTR => B1: 4,9
* DIS B2: 1,5 + B1: 4,9 # E3: 4,9 => CTR => E3: 8
* PRF B2: 1,5 + B1: 4,9 + E3: 8 => SOL
* STA B2: 1,5 + B1: 4,9 + E3: 8
* CNT   4 HDP CHAINS /   5 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Mar&YEAR=2019, 20190309, absurd

Solution

position: 341269875856174923792385146183456297429837651567921384218543769975618432634792518 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: 4,9 => UNS
* DIS # B2: 4,9 => CTR => B2: 1,5
* INC # B2: 1,5 => UNS
* INC # E3: 4,9 => UNS
* PRF # E3: 8 => SOL
* INC # A1: 2,3 => UNS
* DIS # C1: 2,3 => CTR => C1: 1,5
* INC # C1: 1,5 => UNS
* INC # D1: 2,3 => UNS
* INC # D1: 1,4,8 => UNS
* INC # G1: 4,8 => UNS
* DIS # H1: 4,8 => CTR => H1: 5,7
* INC # H1: 5,7 => UNS
* INC # E3: 4,8 => UNS
* INC # E3: 9 => UNS
* DIS # G4: 3,8 => CTR => G4: 2,6
* INC # G4: 2,6 => UNS
* INC # A9: 2,6 => UNS
* DIS # A9: 5 => CTR => A9: 2,6
* DIS # G9: 2,9 => CTR => G9: 5,6
* INC # G9: 5,6 => UNS
* DIS # F7: 2,9 => CTR => F7: 3,4,8
* INC # F7: 3,4,8 => UNS
* DIS # G8: 2,5 => CTR => G8: 3,4
* INC # G8: 3,4 => UNS
* INC # G9: 2,5 => UNS
* INC # C8: 2,5 => UNS
* DIS # C8: 1,8 => CTR => C8: 2,5
* CNT  28 HDP CHAINS /  28 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # B1: 4,9 => UNS
* DIS # B2: 4,9 => CTR => B2: 1,5
* INC B2: 1,5 # B1: 4,9 => UNS
* DIS B2: 1,5 # B1: 1,5 => CTR => B1: 4,9
* DIS B2: 1,5 + B1: 4,9 # E3: 4,9 => CTR => E3: 8
* PRF B2: 1,5 + B1: 4,9 + E3: 8 => SOL
* STA B2: 1,5 + B1: 4,9 + E3: 8
* CNT   6 HDP CHAINS /   5 HYP OPENED