Analysis of zz-www.sudokuoftheday.co.uk-20060618-absurd-base.sdk

Contents

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

level: medium

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

position: ..3.2....1278..39.95....6......9.18.51...2..........3.74..5......1.349..3......7. initial

Autosolve

position: ..3.2....1278..39.95...36...3..9.18.51.3.2....7.....3.74..5...3..17349..395....7. autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* PRF # A1: 4 => SOL
* DIS # A1: 6 => CTR => A1: 4,8
* PRF # I3: 1,2,7 => SOL
* DIS # E5: 4,6 => CTR => E5: 7,8
* DIS # F4: 5,6 => CTR => F4: 7
* PRF # D1: 1,4 => SOL
* DIS # E3: 1,4 => CTR => E3: 7
* DIS # H3: 1,4 => CTR => H3: 2
* PRF # I3: 1,4 => SOL
* DIS # G1: 4,5 => CTR => G1: 7,8
* DIS # I1: 4,5 => CTR => I1: 1,7,8
* DIS # I4: 4,7 => CTR => I4: 2,5,6
* DIS # I5: 4,7 => CTR => I5: 6,9
* DIS # E5: 4,7 => CTR => E5: 6,8
* DIS # G1: 4,7 => CTR => G1: 5,8
* DIS # E5: 4,6 => CTR => E5: 7,8
* DIS # A8: 6,8 => CTR => A8: 2
* DIS # G9: 2,8 => CTR => G9: 4
* PRF # I9: 2,8 => SOL
* CNT  19 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:

* PRF # A1: 4 => SOL
* STA A1: 4
* CNT   1 HDP CHAINS /   2 HYP OPENED

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

Details

Positions

..3.2....1278..39.95....6......9.18.51...2..........3.74..5......1.349..3......7. initial
..3.2....1278..39.95...36...3..9.18.51.3.2....7.....3.74..5...3..17349..395....7. autosolve
463129857127865394958473621634597182519382746872641539746958213281734965395216478 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (10)
B1: 6,8
C3: 4,8
E2: 4,6
F2: 5,6
D3: 1,4
I2: 4,5
G5: 4,7
H5: 4,6
B8: 6,8
G7: 2,8

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
H7,I9: 1.. / H7 = 1  => 17 pairs (_) / I9 = 1  => 19 pairs (_)
H3,I3: 2.. / H3 = 2  => 12 pairs (_) / I3 = 2  =>  0 pairs (X)
C7,A8: 2.. / C7 = 2  =>  0 pairs (X) / A8 = 2  => 13 pairs (_)
D7,D9: 2.. / D7 = 2  =>  0 pairs (X) / D9 = 2  => 11 pairs (_)
A1,C3: 4.. / A1 = 4  =>  0 pairs (*) / C3 = 4  =>  0 pairs (X)
G9,I9: 4.. / G9 = 4  => 11 pairs (_) / I9 = 4  =>  0 pairs (X)
E2,I2: 4.. / E2 = 4  =>  0 pairs (X) / I2 = 4  =>  0 pairs (_)
H8,I8: 5.. / H8 = 5  => 11 pairs (_) / I8 = 5  =>  0 pairs (*)
F2,I2: 5.. / F2 = 5  =>  0 pairs (*) / I2 = 5  =>  0 pairs (X)
G1,G6: 5.. / G1 = 5  =>  0 pairs (X) / G6 = 5  => 16 pairs (_)
H1,H8: 5.. / H1 = 5  =>  0 pairs (*) / H8 = 5  =>  0 pairs (X)
A1,B1: 6.. / A1 = 6  =>  0 pairs (X) / B1 = 6  => 11 pairs (_)
E2,F2: 6.. / E2 = 6  =>  0 pairs (*) / F2 = 6  =>  0 pairs (X)
B1,B8: 6.. / B1 = 6  => 11 pairs (_) / B8 = 6  =>  0 pairs (X)
F1,E3: 7.. / F1 = 7  =>  0 pairs (X) / E3 = 7  => 10 pairs (_)
F4,E5: 7.. / F4 = 7  => 10 pairs (_) / E5 = 7  =>  0 pairs (X)
E3,I3: 7.. / E3 = 7  => 10 pairs (_) / I3 = 7  =>  0 pairs (X)
F4,I4: 7.. / F4 = 7  => 10 pairs (_) / I4 = 7  =>  0 pairs (X)
E3,E5: 7.. / E3 = 7  => 10 pairs (_) / E5 = 7  =>  0 pairs (X)
F1,F4: 7.. / F1 = 7  =>  0 pairs (X) / F4 = 7  => 10 pairs (_)
G1,G5: 7.. / G1 = 7  =>  0 pairs (X) / G5 = 7  =>  9 pairs (_)
C3,I3: 8.. / C3 = 8  =>  0 pairs (*) / I3 = 8  =>  0 pairs (X)
C5,E5: 8.. / C5 = 8  =>  0 pairs (X) / E5 = 8  => 11 pairs (_)
B1,B8: 8.. / B1 = 8  =>  0 pairs (X) / B8 = 8  => 11 pairs (_)
D1,F1: 9.. / D1 = 9  => 12 pairs (_) / F1 = 9  => 12 pairs (_)
C5,C6: 9.. / C5 = 9  => 13 pairs (_) / C6 = 9  => 10 pairs (_)
I5,I6: 9.. / I5 = 9  => 10 pairs (_) / I6 = 9  => 13 pairs (_)
D7,F7: 9.. / D7 = 9  => 12 pairs (_) / F7 = 9  => 12 pairs (_)
C5,I5: 9.. / C5 = 9  => 13 pairs (_) / I5 = 9  => 10 pairs (_)
C6,I6: 9.. / C6 = 9  => 10 pairs (_) / I6 = 9  => 13 pairs (_)
D1,D7: 9.. / D1 = 9  => 12 pairs (_) / D7 = 9  => 12 pairs (_)
F1,F7: 9.. / F1 = 9  => 12 pairs (_) / F7 = 9  => 12 pairs (_)
* DURATION: 0:00:31.803165  START: 23:55:52.560254  END: 23:56:24.363419 2019-04-30
* CP COUNT: (32)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (B1,B8,C3,D3,E2,F2,G5,G7,H5,I2)
* ..3.2....1278..39.95...36...3..9.18.51.3.2....7.....3.74..5...3..17349..395....7.
* PAIR B1: 6,8 BLK 1
A1: 6,8,4                                # reduction candidate for 6,8
A1: 4 => SOLVED
* 463129857127865394958473621634597182519382746872641539746958213281734965395216478
A1: 6,8                                  # 17 pairs
* PAIR C3: 4,8 BLK 1
A1: 4,8,6                                # reduction candidate for 4,8
A1: 6 => CTR
* 683.2.5.71278.539495417362823649718551.3.274.47.5..23.7426598.38617349523952..47.
A1: 4,8                                  # 11 pairs
* PAIR C3: 4,8 ROW 3
I3: 4,8,1,2,7                            # reduction candidate for 4,8
I3: 1,2,7 => SOLVED
* 463129857127865394958473621634597182519382746872641539746958213281734965395216478
I3: 4,8                                  # 14 pairs
* PAIR C3: 4,8 COL C
C5: 4,8,6,9                              # reduction candidate for 4,8
C5: 4,8                                  # 13 pairs
C6: 4,8,2,6,9                            # reduction candidate for 4,8
C6: 4,8                                  # 16 pairs
* PAIR E2: 4,6 COL E
E5: 4,6,7,8                              # reduction candidate for 4,6
E5: 4,6 => CTR
* ..3.2..171278..39.954173628.3..9718.5183.2749.79.18.3.74..51863..1734952395286471
E5: 7,8                                  # 11 pairs
E6: 4,6,1,8                              # reduction candidate for 4,6
E6: 4,6                                  # 14 pairs
* PAIR F2: 5,6 COL F
F4: 5,6,7                                # reduction candidate for 5,6
F4: 5,6 => CTR
* ..3.27...1278..39.95...36.7.3..9.18.51.372469.79....3.74..59..3..17349..395....74
F4: 7                                    # 10 pairs
F6: 5,6,1,8                              # reduction candidate for 5,6
F6: 5,6                                  # 14 pairs
* PAIR D3: 1,4 BLK 2
D1: 1,4,5,9                              # reduction candidate for 1,4
D1: 1,4 => SOLVED
* 463129857127865394958473621634597182519382746872641539746958213281734965395216478
D1: 5,9                                  # 11 pairs
E3: 1,4,7                                # reduction candidate for 1,4
E3: 1,4 => CTR
* ..3.27...1278..39.95...36.7.3..9.18.51.372469.79....3.74..59..3..17349..395....74
E3: 7                                    # 10 pairs
* PAIR D3: 1,4 ROW 3
H3: 1,4,2                                # reduction candidate for 1,4
H3: 1,4 => CTR
* ..3.2.5..1278..39.95...36.2.3..9.18.51.3.2....7....23.74..5.8.3..17349..3952..47.
H3: 2                                    # 12 pairs
I3: 1,4,2,7,8                            # reduction candidate for 1,4
I3: 1,4 => SOLVED
* 463129857127865394958473621634597182519382746872641539746958213281734965395216478
I3: 2,7,8                                # 10 pairs
* PAIR D3: 1,4 COL D
D6: 1,4,5,6                              # reduction candidate for 1,4
D6: 1,4                                  # 14 pairs
D6: 5,6                                  # 11 pairs
* PAIR I2: 4,5 BLK 3
G1: 4,5,7,8                              # reduction candidate for 4,5
G1: 4,5 => CTR
* ..3.295171278.5394954173628.3..9718.51.3427...7..1..3.74..51.63..17349523952..471
G1: 7,8                                  # 17 pairs
H1: 4,5,1                                # reduction candidate for 4,5
H1: 4,5                                  # 17 pairs
I1: 4,5,1,7,8                            # reduction candidate for 4,5
I1: 4,5 => CTR
* ..3.2..1.1278..39.95...362..3..9.18.51.3.274..7....53.74..5.2632617349583952..471
I1: 1,7,8                                # 10 pairs
* PAIR I2: 4,5 COL I
I4: 4,5,2,6,7                            # reduction candidate for 4,5
I4: 4,5                                  # 14 pairs
I6: 4,5,2,6,9                            # reduction candidate for 4,5
I6: 4,5                                  # 15 pairs
* PAIR G5: 4,7 BLK 6
I4: 4,7,2,5,6                            # reduction candidate for 4,7
I4: 4,7 => CTR
* ..3.2....12784639595.1736...3..9718451438276987946153274..5..13..17349..395....7.
I4: 2,5,6                                # 10 pairs
I5: 4,7,6,9                              # reduction candidate for 4,7
I5: 4,7 => CTR
* ..3925.41127846395954173628436597182519382.67.7.46153974.659813..173495.395.18.7.
I5: 6,9                                  # 11 pairs
* PAIR G5: 4,7 ROW 5
E5: 4,7,6,8                              # reduction candidate for 4,7
E5: 4,7 => CTR
* ..3.2....1278..39.954173628.3..9718.518342769.79....3.74..5..13..173495.395....7.
E5: 6,8                                  # 11 pairs
* PAIR G5: 4,7 COL G
G1: 4,7,5,8                              # reduction candidate for 4,7
G1: 4,7 => CTR
* .63.2....127846395954173628.32.9718651.3.2....7....53.746.5..132817349..395....74
G1: 5,8                                  # 10 pairs
* PAIR H5: 4,6 BLK 6
I4: 4,6,2,5,7                            # reduction candidate for 4,6
I4: 4,6                                  # 12 pairs
I5: 4,6,7,9                              # reduction candidate for 4,6
I5: 4,6                                  # 13 pairs
I6: 4,6,2,5,9                            # reduction candidate for 4,6
I6: 4,6                                  # 12 pairs
* PAIR H5: 4,6 ROW 5
C5: 4,6,8,9                              # reduction candidate for 4,6
C5: 4,6                                  # 13 pairs
E5: 4,6,7,8                              # reduction candidate for 4,6
E5: 4,6 => CTR
* ..3.2..171278..39.954173628.3..9718.5183.2749.79.18.3.74..51863..1734952395286471
E5: 7,8                                  # 11 pairs
* PAIR B8: 6,8 BLK 7
C7: 6,8,2                                # reduction candidate for 6,8
C7: 6,8                                  # 13 pairs
A8: 6,8,2                                # reduction candidate for 6,8
A8: 6,8 => CTR
* ..3.2.5..1278.539495..736..23..9718.51.3.274..7..4.23.742.5.8.3..1734952395218476
A8: 2                                    # 13 pairs
* PAIR B8: 6,8 ROW 8
I8: 6,8,2,5                              # reduction candidate for 6,8
I8: 6,8                                  # 14 pairs
I8: 2,5                                  # 12 pairs
* PAIR G7: 2,8 BLK 9
I8: 2,8,5,6                              # reduction candidate for 2,8
I8: 2,8                                  # 17 pairs
G9: 2,8,4                                # reduction candidate for 2,8
G9: 2,8 => CTR
* .63.25.41127846395954173628.3.59718251.3.2467.7.461539746.5..13..1734956395....74
G9: 4                                    # 11 pairs
I9: 2,8,1,4,6                            # reduction candidate for 2,8
I9: 2,8 => SOLVED
* 463129857127865394958473621634597182519382746872641539746958213281734965395216478
I9: 1,4,6                                # 10 pairs
* PAIR G7: 2,8 ROW 7
C7: 2,8,6                                # reduction candidate for 2,8
C7: 2,8                                  # 16 pairs
C7: 6                                    # 14 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060618-absurd-base-pr-000.dot
* REASONING
* PRF # A1: 4 => SOL
* DIS # A1: 6 => CTR => A1: 4,8
* PRF # I3: 1,2,7 => SOL
* DIS # E5: 4,6 => CTR => E5: 7,8
* DIS # F4: 5,6 => CTR => F4: 7
* PRF # D1: 1,4 => SOL
* DIS # E3: 1,4 => CTR => E3: 7
* DIS # H3: 1,4 => CTR => H3: 2
* PRF # I3: 1,4 => SOL
* DIS # G1: 4,5 => CTR => G1: 7,8
* DIS # I1: 4,5 => CTR => I1: 1,7,8
* DIS # I4: 4,7 => CTR => I4: 2,5,6
* DIS # I5: 4,7 => CTR => I5: 6,9
* DIS # E5: 4,7 => CTR => E5: 6,8
* DIS # G1: 4,7 => CTR => G1: 5,8
* DIS # E5: 4,6 => CTR => E5: 7,8
* DIS # A8: 6,8 => CTR => A8: 2
* DIS # G9: 2,8 => CTR => G9: 4
* PRF # I9: 2,8 => SOL
* CNT  19 HDP CHAINS /  57 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (B1,B8,C3,D3,E2,F2,G5,G7,H5,I2)
* ..3.2....1278..39.95...36...3..9.18.51.3.2....7.....3.74..5...3..17349..395....7.
* PAIR B1: 6,8 BLK 1
A1: 6,8,4                                # reduction candidate for 6,8
A1: 4 => SOLVED
* 463129857127865394958473621634597182519382746872641539746958213281734965395216478
* DURATION: 0:00:02.396041  START: 23:56:56.221548  END: 23:56:58.617589 2019-04-30
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060618-absurd-base-pr-001.dot
* REASONING
* PRF # A1: 4 => SOL
* STA A1: 4
* CNT   1 HDP CHAINS /   2 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Jun&YEAR=2006, 20060618, absurd

Solution

position: 463129857127865394958473621634597182519382746872641539746958213281734965395216478 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 # A1: 6,8 => UNS
* PRF # A1: 4 => SOL
* INC # A1: 4,8 => UNS
* DIS # A1: 6 => CTR => A1: 4,8
* INC # I3: 4,8 => UNS
* PRF # I3: 1,2,7 => SOL
* INC # C5: 4,8 => UNS
* INC # C6: 4,8 => UNS
* DIS # E5: 4,6 => CTR => E5: 7,8
* INC # E5: 7,8 => UNS
* INC # E6: 4,6 => UNS
* DIS # F4: 5,6 => CTR => F4: 7
* INC # F4: 7 => UNS
* INC # F6: 5,6 => UNS
* PRF # D1: 1,4 => SOL
* INC # D1: 5,9 => UNS
* DIS # E3: 1,4 => CTR => E3: 7
* INC # E3: 7 => UNS
* DIS # H3: 1,4 => CTR => H3: 2
* INC # H3: 2 => UNS
* PRF # I3: 1,4 => SOL
* INC # I3: 2,7,8 => UNS
* INC # D6: 1,4 => UNS
* INC # D6: 5,6 => UNS
* DIS # G1: 4,5 => CTR => G1: 7,8
* INC # G1: 7,8 => UNS
* INC # H1: 4,5 => UNS
* DIS # I1: 4,5 => CTR => I1: 1,7,8
* INC # I1: 1,7,8 => UNS
* INC # I4: 4,5 => UNS
* INC # I6: 4,5 => UNS
* DIS # I4: 4,7 => CTR => I4: 2,5,6
* INC # I4: 2,5,6 => UNS
* DIS # I5: 4,7 => CTR => I5: 6,9
* INC # I5: 6,9 => UNS
* DIS # E5: 4,7 => CTR => E5: 6,8
* INC # E5: 6,8 => UNS
* DIS # G1: 4,7 => CTR => G1: 5,8
* INC # G1: 5,8 => UNS
* INC # I4: 4,6 => UNS
* INC # I5: 4,6 => UNS
* INC # I6: 4,6 => UNS
* INC # C5: 4,6 => UNS
* DIS # E5: 4,6 => CTR => E5: 7,8
* INC # E5: 7,8 => UNS
* INC # C7: 6,8 => UNS
* DIS # A8: 6,8 => CTR => A8: 2
* INC # A8: 2 => UNS
* INC # I8: 6,8 => UNS
* INC # I8: 2,5 => UNS
* INC # I8: 2,8 => UNS
* DIS # G9: 2,8 => CTR => G9: 4
* INC # G9: 4 => UNS
* PRF # I9: 2,8 => SOL
* INC # I9: 1,4,6 => UNS
* INC # C7: 2,8 => UNS
* INC # C7: 6 => UNS
* CNT  57 HDP CHAINS /  57 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # A1: 6,8 => UNS
* PRF # A1: 4 => SOL
* STA A1: 4
* CNT   2 HDP CHAINS /   2 HYP OPENED