Analysis of zz-www.sudokuoftheday.co.uk-20060424-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: ....57....4.32.....8..1.2..2...3.4....1...3.5......712..26.31.97.45.....396.....7 initial

Autosolve

position: .2..57....4.32.....8..1.2..2...3.4....1...3.5.3..6.7128526731497145.....396.....7 autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* PRF # D1: 4,9 => SOL
* DIS # D1: 8 => CTR => D1: 4,9
* DIS # F3: 4,9 => CTR => F3: 6
* DIS # D6: 4,9 => CTR => D6: 8
* PRF # D6: 8 => SOL
* DIS # A6: 5 => CTR => A6: 4,9
* DIS # F5: 4,9 => CTR => F5: 2,8
* DIS # H4: 6,8 => CTR => H4: 9
* PRF # I1: 6,8 => SOL
* DIS # I2: 6,8 => CTR => I2: 1
* DIS # I8: 6,8 => CTR => I8: 3
* DIS # F8: 2 => CTR => F8: 8,9
* DIS # E5: 4 => CTR => E5: 8,9
* DIS # F9: 4,8 => CTR => F9: 1,2
* DIS # F9: 4,8 => CTR => F9: 1,2
* DIS # H8: 6,8 => CTR => H8: 2,3
* DIS # I8: 6,8 => CTR => I8: 3
* DIS # G2: 6,8 => CTR => G2: 5,9
* DIS # H9: 2 => CTR => H9: 5,8
* CNT  19 HDP CHAINS /  43 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 # D1: 4,9 => SOL
* STA D1: 4,9
* CNT   1 HDP CHAINS /   3 HYP OPENED

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

Details

Positions

....57....4.32.....8..1.2..2...3.4....1...3.5......712..26.31.97.45.....396.....7 initial
.2..57....4.32.....8..1.2..2...3.4....1...3.5.3..6.7128526731497145.....396.....7 autosolve
123457968649328571587916234278135496461792385935864712852673149714589623396241857 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (13)
C1: 3,9
D3: 4,9
B4: 6,7
A5: 4,9
B5: 6,7
D4: 1,7
D5: 2,7
I4: 6,8
E8: 8,9
D9: 1,2
E9: 4,8
G8: 6,8
G9: 5,8

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
A1,A2: 1.. / A1 = 1  => 14 pairs (_) / A2 = 1  =>  0 pairs (X)
I1,I2: 1.. / I1 = 1  =>  0 pairs (X) / I2 = 1  => 14 pairs (_)
D4,F4: 1.. / D4 = 1  => 23 pairs (_) / F4 = 1  =>  0 pairs (X)
D9,F9: 1.. / D9 = 1  =>  0 pairs (X) / F9 = 1  => 23 pairs (_)
A1,I1: 1.. / A1 = 1  => 14 pairs (_) / I1 = 1  =>  0 pairs (X)
A2,I2: 1.. / A2 = 1  =>  0 pairs (X) / I2 = 1  => 14 pairs (_)
D4,D9: 1.. / D4 = 1  => 23 pairs (_) / D9 = 1  =>  0 pairs (X)
F4,F9: 1.. / F4 = 1  =>  0 pairs (X) / F9 = 1  => 23 pairs (_)
D5,F5: 2.. / D5 = 2  =>  0 pairs (X) / F5 = 2  => 23 pairs (_)
H8,H9: 2.. / H8 = 2  => 29 pairs (_) / H9 = 2  =>  0 pairs (X)
F8,H8: 2.. / F8 = 2  =>  0 pairs (X) / H8 = 2  => 29 pairs (_)
D5,D9: 2.. / D5 = 2  =>  0 pairs (X) / D9 = 2  => 23 pairs (_)
C1,C3: 3.. / C1 = 3  => 16 pairs (_) / C3 = 3  => 21 pairs (_)
H8,I8: 3.. / H8 = 3  =>  0 pairs (X) / I8 = 3  => 26 pairs (_)
I1,I3: 4.. / I1 = 4  =>  0 pairs (X) / I3 = 4  =>  0 pairs (_)
A5,A6: 4.. / A5 = 4  => 13 pairs (_) / A6 = 4  => 21 pairs (_)
E9,F9: 4.. / E9 = 4  => 13 pairs (_) / F9 = 4  =>  0 pairs (X)
D1,I1: 4.. / D1 = 4  =>  0 pairs (*) / I1 = 4  =>  0 pairs (X)
E5,E9: 4.. / E5 = 4  =>  0 pairs (X) / E9 = 4  => 13 pairs (_)
F4,F6: 5.. / F4 = 5  =>  0 pairs (*) / F6 = 5  =>  0 pairs (X)
G9,H9: 5.. / G9 = 5  => 15 pairs (_) / H9 = 5  => 21 pairs (_)
C4,F4: 5.. / C4 = 5  =>  0 pairs (X) / F4 = 5  =>  0 pairs (_)
G2,G9: 5.. / G2 = 5  => 21 pairs (_) / G9 = 5  => 15 pairs (_)
F2,F3: 6.. / F2 = 6  =>  0 pairs (X) / F3 = 6  => 19 pairs (_)
B4,B5: 6.. / B4 = 6  =>  0 pairs (X) / B5 = 6  => 23 pairs (_)
B5,H5: 6.. / B5 = 6  => 23 pairs (_) / H5 = 6  =>  0 pairs (X)
C2,C3: 7.. / C2 = 7  => 13 pairs (_) / C3 = 7  => 17 pairs (_)
H2,H3: 7.. / H2 = 7  => 17 pairs (_) / H3 = 7  => 13 pairs (_)
B4,B5: 7.. / B4 = 7  => 23 pairs (_) / B5 = 7  =>  0 pairs (X)
D4,D5: 7.. / D4 = 7  =>  0 pairs (X) / D5 = 7  => 23 pairs (_)
C2,H2: 7.. / C2 = 7  => 13 pairs (_) / H2 = 7  => 17 pairs (_)
C3,H3: 7.. / C3 = 7  => 17 pairs (_) / H3 = 7  => 13 pairs (_)
B4,D4: 7.. / B4 = 7  => 23 pairs (_) / D4 = 7  =>  0 pairs (X)
B5,D5: 7.. / B5 = 7  =>  0 pairs (X) / D5 = 7  => 23 pairs (_)
D1,F2: 8.. / D1 = 8  =>  0 pairs (X) / F2 = 8  =>  0 pairs (_)
C4,C6: 8.. / C4 = 8  =>  0 pairs (*) / C6 = 8  =>  0 pairs (X)
D1,D6: 8.. / D1 = 8  =>  0 pairs (X) / D6 = 8  =>  0 pairs (_)
G1,G2: 9.. / G1 = 9  => 18 pairs (_) / G2 = 9  => 19 pairs (_)
H4,H5: 9.. / H4 = 9  => 15 pairs (_) / H5 = 9  =>  0 pairs (X)
E8,F8: 9.. / E8 = 9  => 14 pairs (_) / F8 = 9  => 27 pairs (_)
E5,E8: 9.. / E5 = 9  => 27 pairs (_) / E8 = 9  => 14 pairs (_)
* DURATION: 0:00:53.169354  START: 22:37:37.638982  END: 22:38:30.808336 2019-04-30
* CP COUNT: (41)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A5,B4,B5,C1,D3,D4,D5,D9,E8,E9,G8,G9,I4)
* .2..57....4.32.....8..1.2..2...3.4....1...3.5.3..6.7128526731497145.....396.....7
* PAIR C1: 3,9 BLK 1
C3: 3,9,5,7                              # reduction candidate for 3,9
C3: 3,9                                  # 19 pairs
C3: 5,7                                  # 17 pairs
* PAIR D3: 4,9 BLK 2
D1: 4,9,8                                # reduction candidate for 4,9
D1: 4,9 => SOLVED
* 123457968649328571587916234278135496461792385935864712852673149714589623396241857
D1: 8 => CTR
* 123857964.4.32...1.8..1.2.32...3.4.6.61...3.5.3..6.7128526731497145...3.396....27
F3: 4,9,6                                # reduction candidate for 4,9
F3: 4,9 => CTR
* 123857964.4.326..168..1.2.32...3.4.6.61...3.5.3..6.7128526731497145...3.396....27
F3: 6                                    # 19 pairs
* PAIR D3: 4,9 COL D
D6: 4,9,8                                # reduction candidate for 4,9
D6: 4,9 => CTR
* 123857964.4.32...1.8..1.2.32...3.4.6.61...3.5.3..6.7128526731497145...3.396....27
D6: 8 => SOLVED
* 123457968649328571587916234278135496461792385935864712852673149714589623396241857
* PAIR A5: 4,9 BLK 4
A6: 4,9,5                                # reduction candidate for 4,9
A6: 5 => CTR
* .23.57....4.32.....8..1.23.27.1354..4617.23.553..6.7128526731497145..623396241..7
A6: 4,9                                  # 19 pairs
* PAIR A5: 4,9 ROW 5
E5: 4,9,8                                # reduction candidate for 4,9
E5: 4,9                                  # 18 pairs
F5: 4,9,2,8                              # reduction candidate for 4,9
F5: 4,9 => CTR
* .2.857.34.4.32...1.83.1.276265731498.7128.365.38.6571285267314971459.6.339614...7
F5: 2,8                                  # 14 pairs
* PAIR I4: 6,8 BLK 6
H4: 6,8,9                                # reduction candidate for 6,8
H4: 6,8 => CTR
* .2.8579.4.4.32...1.8..1.2.627.13.468461782395.38.6.712852673149714598623396241..7
H4: 9                                    # 15 pairs
H5: 6,8,9                                # reduction candidate for 6,8
H5: 6,8                                  # 15 pairs
* PAIR I4: 6,8 COL I
I1: 6,8,1,3,4                            # reduction candidate for 6,8
I1: 6,8 => SOLVED
* 123457968649328571587916234278135496461792385935864712852673149714589623396241857
I1: 1,3,4                                # 13 pairs
I2: 6,8,1                                # reduction candidate for 6,8
I2: 6,8 => CTR
* .2.457..114.328..6.8.9162.42...3.4.8..1.8.3.5.3..6.7128526731497145....3396.....7
I2: 1                                    # 14 pairs
I8: 6,8,3                                # reduction candidate for 6,8
I8: 6,8 => CTR
* .2..57.8..4.328....8..162..265731498.71289365.3846571285267314971459283639614.527
I8: 3                                    # 26 pairs
* PAIR E8: 8,9 BLK 8
F8: 8,9,2                                # reduction candidate for 8,9
F8: 2 => CTR
* .2.857.34.4.32...1.83.1.276265731498.712..365.38.657128526731497145926833961..527
F8: 8,9                                  # 29 pairs
* PAIR E8: 8,9 COL E
E5: 8,9,4                                # reduction candidate for 8,9
E5: 4 => CTR
* .2.857.34.4.32...1.83419276265731498971248365438965712852673149714592683396184527
E5: 8,9                                  # 13 pairs
* PAIR D9: 1,2 BLK 8
F9: 1,2,4,8                              # reduction candidate for 1,2
F9: 4,8 => CTR
* .2.857.34.4.32...1.83.1.276265731498.712..365.38.657128526731497145926833961..527
F9: 1,2                                  # 29 pairs
* PAIR E9: 4,8 BLK 8
F9: 4,8,1,2                              # reduction candidate for 4,8
F9: 4,8 => CTR
* .2.857.34.4.32...1.83.1.276265731498.712..365.38.657128526731497145926833961..527
F9: 1,2                                  # 29 pairs
* PAIR E9: 4,8 COL E
E5: 4,8,9                                # reduction candidate for 4,8
E5: 9                                    # 27 pairs
E5: 4,8                                  # 14 pairs
* PAIR G8: 6,8 BLK 9
H8: 6,8,2,3                              # reduction candidate for 6,8
H8: 6,8 => CTR
* .29857.3..4.32.....83.1.27.265731498.712..365.38.657128526731497145926833961..527
H8: 2,3                                  # 14 pairs
I8: 6,8,3                                # reduction candidate for 6,8
I8: 6,8 => CTR
* .2..57.8..4.328....8..162..265731498.71289365.3846571285267314971459283639614.527
I8: 3                                    # 26 pairs
* PAIR G8: 6,8 COL G
G1: 6,8,9                                # reduction candidate for 6,8
G1: 6,8                                  # 19 pairs
G2: 6,8,5,9                              # reduction candidate for 6,8
G2: 6,8 => CTR
* 123.57964.4.32.8.1.8..1.2.32...3.4.6.617.23.5.3..6.7128526731497145..6..396...5.7
G2: 5,9                                  # 14 pairs
* PAIR G9: 5,8 BLK 9
H9: 5,8,2                                # reduction candidate for 5,8
H9: 2 => CTR
* .2.857.34.4.32...1.83.1.276265731498.712..365.38.657128526731497145926833961..527
H9: 5,8                                  # 29 pairs
* PAIR G9: 5,8 COL G
G2: 5,8,6,9                              # reduction candidate for 5,8
G2: 5,8                                  # 19 pairs
G2: 6,9                                  # 16 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060424-absurd-base-pr-000.dot
* REASONING
* PRF # D1: 4,9 => SOL
* DIS # D1: 8 => CTR => D1: 4,9
* DIS # F3: 4,9 => CTR => F3: 6
* DIS # D6: 4,9 => CTR => D6: 8
* PRF # D6: 8 => SOL
* DIS # A6: 5 => CTR => A6: 4,9
* DIS # F5: 4,9 => CTR => F5: 2,8
* DIS # H4: 6,8 => CTR => H4: 9
* PRF # I1: 6,8 => SOL
* DIS # I2: 6,8 => CTR => I2: 1
* DIS # I8: 6,8 => CTR => I8: 3
* DIS # F8: 2 => CTR => F8: 8,9
* DIS # E5: 4 => CTR => E5: 8,9
* DIS # F9: 4,8 => CTR => F9: 1,2
* DIS # F9: 4,8 => CTR => F9: 1,2
* DIS # H8: 6,8 => CTR => H8: 2,3
* DIS # I8: 6,8 => CTR => I8: 3
* DIS # G2: 6,8 => CTR => G2: 5,9
* DIS # H9: 2 => CTR => H9: 5,8
* CNT  19 HDP CHAINS /  43 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A5,B4,B5,C1,D3,D4,D5,D9,E8,E9,G8,G9,I4)
* .2..57....4.32.....8..1.2..2...3.4....1...3.5.3..6.7128526731497145.....396.....7
* PAIR C1: 3,9 BLK 1
C3: 3,9,5,7                              # reduction candidate for 3,9
C3: 3,9                                  # 19 pairs
C3: 5,7                                  # 17 pairs
* PAIR D3: 4,9 BLK 2
D1: 4,9,8                                # reduction candidate for 4,9
D1: 4,9 => SOLVED
* 123457968649328571587916234278135496461792385935864712852673149714589623396241857
* DURATION: 0:00:03.106643  START: 22:39:01.110178  END: 22:39:04.216821 2019-04-30
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060424-absurd-base-pr-001.dot
* REASONING
* PRF # D1: 4,9 => SOL
* STA D1: 4,9
* CNT   1 HDP CHAINS /   3 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Apr&YEAR=2006, 20060424, absurd

Solution

position: 123457968649328571587916234278135496461792385935864712852673149714589623396241857 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 # C3: 3,9 => UNS
* INC # C3: 5,7 => UNS
* PRF # D1: 4,9 => SOL
* DIS # D1: 8 => CTR => D1: 4,9
* DIS # F3: 4,9 => CTR => F3: 6
* INC # F3: 6 => UNS
* DIS # D6: 4,9 => CTR => D6: 8
* PRF # D6: 8 => SOL
* INC # A6: 4,9 => UNS
* DIS # A6: 5 => CTR => A6: 4,9
* INC # E5: 4,9 => UNS
* DIS # F5: 4,9 => CTR => F5: 2,8
* INC # F5: 2,8 => UNS
* DIS # H4: 6,8 => CTR => H4: 9
* INC # H4: 9 => UNS
* INC # H5: 6,8 => UNS
* PRF # I1: 6,8 => SOL
* INC # I1: 1,3,4 => UNS
* DIS # I2: 6,8 => CTR => I2: 1
* INC # I2: 1 => UNS
* DIS # I8: 6,8 => CTR => I8: 3
* INC # I8: 3 => UNS
* INC # F8: 8,9 => UNS
* DIS # F8: 2 => CTR => F8: 8,9
* INC # E5: 8,9 => UNS
* DIS # E5: 4 => CTR => E5: 8,9
* INC # F9: 1,2 => UNS
* DIS # F9: 4,8 => CTR => F9: 1,2
* DIS # F9: 4,8 => CTR => F9: 1,2
* INC # F9: 1,2 => UNS
* INC # E5: 4,8 => UNS
* INC # E5: 9 => UNS
* DIS # H8: 6,8 => CTR => H8: 2,3
* INC # H8: 2,3 => UNS
* DIS # I8: 6,8 => CTR => I8: 3
* INC # I8: 3 => UNS
* INC # G1: 6,8 => UNS
* DIS # G2: 6,8 => CTR => G2: 5,9
* INC # G2: 5,9 => UNS
* INC # H9: 5,8 => UNS
* DIS # H9: 2 => CTR => H9: 5,8
* INC # G2: 5,8 => UNS
* INC # G2: 6,9 => UNS
* CNT  43 HDP CHAINS /  43 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # C3: 3,9 => UNS
* INC # C3: 5,7 => UNS
* PRF # D1: 4,9 => SOL
* STA D1: 4,9
* CNT   3 HDP CHAINS /   3 HYP OPENED