Analysis of zz-www.sudokuoftheday.co.uk-20060428-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: 5...9.2....2..54.....4.2.19..5..6.78.8.14.6..........43.726........7....8.6.5.... initial

Autosolve

position: 5...982..932.1548...8432519..5.26.78.8.14.6.....58...43.726.8.....87....8.6.5.7.. autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* PRF # B7: 1,4 => SOL
* DIS # B9: 1,4 => CTR => B9: 2,9
* PRF # C8: 9 => SOL
* PRF # B4: 9 => SOL
* PRF # C6: 1 => SOL
* PRF # G4: 1 => SOL
* PRF # B7: 1,4 => SOL
* DIS # B9: 1,4 => CTR => B9: 2,9
* PRF # F8: 1,4 => SOL
* PRF # F9: 3,9 => SOL
* PRF # F8: 1,4 => SOL
* PRF # G6: 3,9 => SOL
* CNT  12 HDP CHAINS /  52 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 # B7: 1,4 => SOL
* STA B7: 1,4
* CNT   1 HDP CHAINS /   2 HYP OPENED

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

Details

Positions

5...9.2....2..54.....4.2.19..5..6.78.8.14.6..........43.726........7....8.6.5.... initial
5...982..932.1548...8432519..5.26.78.8.14.6.....58...43.726.8.....87....8.6.5.7.. autosolve
514798263932615487678432519495326178783149652261587934347261895159874326826953741 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (18)
B1: 1,4
C1: 1,4
A3: 6,7
B3: 6,7
D1: 6,7
D2: 6,7
H1: 3,6
I2: 6,7
A4: 1,4
A5: 2,7
C5: 3,9
B6: 6,7
D4: 3,9
A8: 1,4
B8: 2,5
D9: 3,9
I7: 1,5
G8: 3,9

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
B1,C1: 1.. / B1 = 1  => 18 pairs (_) / C1 = 1  => 21 pairs (_)
G4,G6: 1.. / G4 = 1  =>  0 pairs (*) / G6 = 1  =>  0 pairs (X)
I7,I9: 1.. / I7 = 1  => 19 pairs (_) / I9 = 1  => 20 pairs (_)
C6,G6: 1.. / C6 = 1  =>  0 pairs (*) / G6 = 1  =>  0 pairs (X)
A4,A8: 1.. / A4 = 1  => 21 pairs (_) / A8 = 1  => 18 pairs (_)
A5,A6: 2.. / A5 = 2  => 21 pairs (_) / A6 = 2  => 18 pairs (_)
B8,B9: 2.. / B8 = 2  => 21 pairs (_) / B9 = 2  => 20 pairs (_)
A6,H6: 2.. / A6 = 2  => 18 pairs (_) / H6 = 2  => 21 pairs (_)
H1,I1: 3.. / H1 = 3  => 20 pairs (_) / I1 = 3  => 17 pairs (_)
C5,C6: 3.. / C5 = 3  => 20 pairs (_) / C6 = 3  => 28 pairs (_)
D4,G4: 3.. / D4 = 3  => 20 pairs (_) / G4 = 3  =>  0 pairs (X)
F8,G8: 3.. / F8 = 3  =>  0 pairs (X) / G8 = 3  =>  0 pairs (_)
D4,D9: 3.. / D4 = 3  => 20 pairs (_) / D9 = 3  =>  0 pairs (X)
B1,C1: 4.. / B1 = 4  => 21 pairs (_) / C1 = 4  => 18 pairs (_)
A4,B4: 4.. / A4 = 4  => 18 pairs (_) / B4 = 4  => 21 pairs (_)
H7,H9: 4.. / H7 = 4  => 19 pairs (_) / H9 = 4  => 19 pairs (_)
A4,A8: 4.. / A4 = 4  => 18 pairs (_) / A8 = 4  => 21 pairs (_)
C1,C8: 4.. / C1 = 4  => 18 pairs (_) / C8 = 4  => 21 pairs (_)
H5,I5: 5.. / H5 = 5  => 21 pairs (_) / I5 = 5  => 21 pairs (_)
B7,B8: 5.. / B7 = 5  => 21 pairs (_) / B8 = 5  => 20 pairs (_)
A3,B3: 6.. / A3 = 6  => 16 pairs (_) / B3 = 6  => 17 pairs (_)
D1,D2: 6.. / D1 = 6  => 16 pairs (_) / D2 = 6  => 16 pairs (_)
A6,B6: 6.. / A6 = 6  => 17 pairs (_) / B6 = 6  => 16 pairs (_)
H8,I8: 6.. / H8 = 6  => 20 pairs (_) / I8 = 6  => 17 pairs (_)
D2,I2: 6.. / D2 = 6  => 16 pairs (_) / I2 = 6  => 16 pairs (_)
A3,A6: 6.. / A3 = 6  => 16 pairs (_) / A6 = 6  => 17 pairs (_)
B3,B6: 6.. / B3 = 6  => 17 pairs (_) / B6 = 6  => 16 pairs (_)
H1,H8: 6.. / H1 = 6  => 17 pairs (_) / H8 = 6  => 20 pairs (_)
A3,B3: 7.. / A3 = 7  => 17 pairs (_) / B3 = 7  => 16 pairs (_)
D1,D2: 7.. / D1 = 7  => 16 pairs (_) / D2 = 7  => 16 pairs (_)
I1,I2: 7.. / I1 = 7  => 16 pairs (_) / I2 = 7  => 16 pairs (_)
F5,F6: 7.. / F5 = 7  => 21 pairs (_) / F6 = 7  => 18 pairs (_)
D1,I1: 7.. / D1 = 7  => 16 pairs (_) / I1 = 7  => 16 pairs (_)
D2,I2: 7.. / D2 = 7  => 16 pairs (_) / I2 = 7  => 16 pairs (_)
A5,F5: 7.. / A5 = 7  => 18 pairs (_) / F5 = 7  => 21 pairs (_)
B3,B6: 7.. / B3 = 7  => 16 pairs (_) / B6 = 7  => 17 pairs (_)
D4,D9: 9.. / D4 = 9  =>  0 pairs (X) / D9 = 9  => 20 pairs (_)
* DURATION: 0:00:47.353251  START: 22:43:24.178379  END: 22:44:11.531630 2019-04-30
* CP COUNT: (37)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A3,A4,A5,A8,B1,B3,B6,B8,C1,C5,D1,D2,D4,D9,G8,H1,I2,I7)
* 5...982..932.1548...8432519..5.26.78.8.14.6.....58...43.726.8.....87....8.6.5.7..
* PAIR B1: 1,4 COL B
B4: 1,4,9                                # reduction candidate for 1,4
B4: 1,4                                  # 27 pairs
B7: 1,4,5,9                              # reduction candidate for 1,4
B7: 1,4 => SOLVED
* 514798263932615487678432519495326178783149652261587934347261895159874326826953741
B7: 5,9                                  # 19 pairs
B9: 1,4,2,9                              # reduction candidate for 1,4
B9: 1,4 => CTR
* 5.4.982..932.1548...8432519.95326178.8314.6.5..158.93435726.8.11298743..8.6.5.7.2
B9: 2,9                                  # 19 pairs
* PAIR C1: 1,4 COL C
C8: 1,4,9                                # reduction candidate for 1,4
C8: 9 => SOLVED
* 514798263932615487678432519495326178783149652261587934347261895159874326826953741
C8: 1,4                                  # 27 pairs
* PAIR A3: 6,7 COL A
A6: 6,7,2                                # reduction candidate for 6,7
A6: 6,7                                  # 21 pairs
A6: 2                                    # 18 pairs
* PAIR D1: 6,7 ROW 1
I1: 6,7,3                                # reduction candidate for 6,7
I1: 6,7                                  # 20 pairs
I1: 3                                    # 17 pairs
* PAIR H1: 3,6 BLK 3
I1: 3,6,7                                # reduction candidate for 3,6
I1: 7                                    # 16 pairs
I1: 3,6                                  # 16 pairs
* PAIR I2: 6,7 BLK 3
I1: 6,7,3                                # reduction candidate for 6,7
I1: 6,7                                  # 20 pairs
I1: 3                                    # 17 pairs
* PAIR A4: 1,4 BLK 4
B4: 1,4,9                                # reduction candidate for 1,4
B4: 9 => SOLVED
* 514798263932615487678432519495326178783149652261587934347261895159874326826953741
B4: 1,4                                  # 27 pairs
* PAIR A5: 2,7 BLK 4
A6: 2,7,6                                # reduction candidate for 2,7
A6: 6                                    # 17 pairs
A6: 2,7                                  # 16 pairs
* PAIR C5: 3,9 BLK 4
C6: 3,9,1                                # reduction candidate for 3,9
C6: 1 => SOLVED
* 514798263932615487678432519495326178783149652261587934347261895159874326826953741
C6: 3,9                                  # 27 pairs
* PAIR C5: 3,9 ROW 5
F5: 3,9,7                                # reduction candidate for 3,9
F5: 3,9                                  # 18 pairs
H5: 3,9,2,5                              # reduction candidate for 3,9
H5: 3,9                                  # 23 pairs
* PAIR B6: 6,7 BLK 4
A6: 6,7,2                                # reduction candidate for 6,7
A6: 6,7                                  # 21 pairs
A6: 2                                    # 18 pairs
* PAIR D4: 3,9 BLK 5
F5: 3,9,7                                # reduction candidate for 3,9
F5: 3,9                                  # 18 pairs
F6: 3,9,7                                # reduction candidate for 3,9
F6: 3,9                                  # 21 pairs
* PAIR D4: 3,9 ROW 4
G4: 3,9,1                                # reduction candidate for 3,9
G4: 1 => SOLVED
* 514798263932615487678432519495326178783149652261587934347261895159874326826953741
G4: 3,9                                  # 27 pairs
* PAIR A8: 1,4 BLK 7
B7: 1,4,5,9                              # reduction candidate for 1,4
B7: 1,4 => SOLVED
* 514798263932615487678432519495326178783149652261587934347261895159874326826953741
B7: 5,9                                  # 19 pairs
C8: 1,4,9                                # reduction candidate for 1,4
C8: 1,4                                  # 27 pairs
B9: 1,4,2,9                              # reduction candidate for 1,4
B9: 1,4 => CTR
* 5.4.982..932.1548...8432519.95326178.8314.6.5..158.93435726.8.11298743..8.6.5.7.2
B9: 2,9                                  # 19 pairs
* PAIR A8: 1,4 ROW 8
F8: 1,4,3,9                              # reduction candidate for 1,4
F8: 1,4 => SOLVED
* 514798263932615487678432519495326178783149652261587934347261895159874326826953741
F8: 3,9                                  # 27 pairs
* PAIR B8: 2,5 ROW 8
H8: 2,5,6                                # reduction candidate for 2,5
H8: 2,5                                  # 17 pairs
I8: 2,5,6                                # reduction candidate for 2,5
I8: 2,5                                  # 20 pairs
* PAIR D9: 3,9 BLK 8
F8: 3,9,1,4                              # reduction candidate for 3,9
F8: 3,9                                  # 27 pairs
F9: 3,9,1,4                              # reduction candidate for 3,9
F9: 3,9 => SOLVED
* 514798263932615487678432519495326178783149652261587934347261895159874326826953741
F9: 1,4                                  # 19 pairs
* PAIR D9: 3,9 ROW 9
H9: 3,9,2,4                              # reduction candidate for 3,9
H9: 3,9                                  # 22 pairs
H9: 2,4                                  # 19 pairs
* PAIR I7: 1,5 ROW 7
B7: 1,5,4,9                              # reduction candidate for 1,5
B7: 4,9                                  # 21 pairs
B7: 1,5                                  # 21 pairs
* PAIR G8: 3,9 BLK 9
H9: 3,9,2,4                              # reduction candidate for 3,9
H9: 3,9                                  # 22 pairs
H9: 2,4                                  # 19 pairs
* PAIR G8: 3,9 ROW 8
F8: 3,9,1,4                              # reduction candidate for 3,9
F8: 1,4 => SOLVED
* 514798263932615487678432519495326178783149652261587934347261895159874326826953741
F8: 3,9                                  # 27 pairs
* PAIR G8: 3,9 COL G
G4: 3,9,1                                # reduction candidate for 3,9
G4: 3,9                                  # 27 pairs
G6: 3,9,1                                # reduction candidate for 3,9
G6: 3,9 => SOLVED
* 514798263932615487678432519495326178783149652261587934347261895159874326826953741
G6: 1                                    # 27 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060428-absurd-base-pr-000.dot
* REASONING
* PRF # B7: 1,4 => SOL
* DIS # B9: 1,4 => CTR => B9: 2,9
* PRF # C8: 9 => SOL
* PRF # B4: 9 => SOL
* PRF # C6: 1 => SOL
* PRF # G4: 1 => SOL
* PRF # B7: 1,4 => SOL
* DIS # B9: 1,4 => CTR => B9: 2,9
* PRF # F8: 1,4 => SOL
* PRF # F9: 3,9 => SOL
* PRF # F8: 1,4 => SOL
* PRF # G6: 3,9 => SOL
* CNT  12 HDP CHAINS /  52 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A3,A4,A5,A8,B1,B3,B6,B8,C1,C5,D1,D2,D4,D9,G8,H1,I2,I7)
* 5...982..932.1548...8432519..5.26.78.8.14.6.....58...43.726.8.....87....8.6.5.7..
* PAIR B1: 1,4 COL B
B4: 1,4,9                                # reduction candidate for 1,4
B4: 1,4                                  # 27 pairs
B7: 1,4,5,9                              # reduction candidate for 1,4
B7: 1,4 => SOLVED
* 514798263932615487678432519495326178783149652261587934347261895159874326826953741
* DURATION: 0:00:02.459085  START: 22:44:51.876663  END: 22:44:54.335748 2019-04-30
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060428-absurd-base-pr-001.dot
* REASONING
* PRF # B7: 1,4 => SOL
* STA B7: 1,4
* CNT   1 HDP CHAINS /   2 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Apr&YEAR=2006, 20060428, absurd

Solution

position: 514798263932615487678432519495326178783149652261587934347261895159874326826953741 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 # B4: 1,4 => UNS
* PRF # B7: 1,4 => SOL
* INC # B7: 5,9 => UNS
* DIS # B9: 1,4 => CTR => B9: 2,9
* INC # B9: 2,9 => UNS
* INC # C8: 1,4 => UNS
* PRF # C8: 9 => SOL
* INC # A6: 6,7 => UNS
* INC # A6: 2 => UNS
* INC # I1: 6,7 => UNS
* INC # I1: 3 => UNS
* INC # I1: 3,6 => UNS
* INC # I1: 7 => UNS
* INC # I1: 6,7 => UNS
* INC # I1: 3 => UNS
* INC # B4: 1,4 => UNS
* PRF # B4: 9 => SOL
* INC # A6: 2,7 => UNS
* INC # A6: 6 => UNS
* INC # C6: 3,9 => UNS
* PRF # C6: 1 => SOL
* INC # F5: 3,9 => UNS
* INC # H5: 3,9 => UNS
* INC # A6: 6,7 => UNS
* INC # A6: 2 => UNS
* INC # F5: 3,9 => UNS
* INC # F6: 3,9 => UNS
* INC # G4: 3,9 => UNS
* PRF # G4: 1 => SOL
* PRF # B7: 1,4 => SOL
* INC # B7: 5,9 => UNS
* INC # C8: 1,4 => UNS
* DIS # B9: 1,4 => CTR => B9: 2,9
* INC # B9: 2,9 => UNS
* PRF # F8: 1,4 => SOL
* INC # F8: 3,9 => UNS
* INC # H8: 2,5 => UNS
* INC # I8: 2,5 => UNS
* INC # F8: 3,9 => UNS
* PRF # F9: 3,9 => SOL
* INC # F9: 1,4 => UNS
* INC # H9: 3,9 => UNS
* INC # H9: 2,4 => UNS
* INC # B7: 1,5 => UNS
* INC # B7: 4,9 => UNS
* INC # H9: 3,9 => UNS
* INC # H9: 2,4 => UNS
* INC # F8: 3,9 => UNS
* PRF # F8: 1,4 => SOL
* INC # G4: 3,9 => UNS
* PRF # G6: 3,9 => SOL
* INC # G6: 1 => UNS
* CNT  52 HDP CHAINS /  52 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # B4: 1,4 => UNS
* PRF # B7: 1,4 => SOL
* STA B7: 1,4
* CNT   2 HDP CHAINS /   2 HYP OPENED