Analysis of zz-www.sudokuoftheday.co.uk-20060521-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: ...973.48.83..4...7...2.....7...15.......9.....9.38.2........5.8.1.....6.52.1...3 initial

Autosolve

position: ...973.48.831.4...7..82.....7...15.......9.....9.38.2...7.8..5.8.1.9..76.52.17..3 autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # B3: 4,6 => CTR => B3: 1,9
* PRF # C4: 4,6 => SOL
* DIS # G2: 6,9 => CTR => G2: 2,7
* PRF # G3: 6,9 => SOL
* DIS # A2: 2 => CTR => A2: 6,9
* DIS # D5: 2,6 => CTR => D5: 5,7
* DIS # E5: 5 => CTR => E5: 4,6
* PRF # C4: 4,6 => SOL
* DIS # I7: 4,9 => CTR => I7: 1,2
* DIS # B7: 3,4 => CTR => B7: 6,9
* DIS # D8: 5 => CTR => D8: 3,4
* DIS # A9: 9 => CTR => A9: 4,6
* DIS # G9: 4 => CTR => G9: 8,9
* PRF # H4: 8,9 => SOL
* CNT  14 HDP CHAINS /  48 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 # B3: 4,6 => CTR => B3: 1,9
* DIS B3: 1,9 # G2: 6,9 => CTR => G2: 2,7
* PRF B3: 1,9 + G2: 2,7 # G3: 6,9 => SOL
* STA B3: 1,9 + G2: 2,7 + G3: 6,9
* CNT   3 HDP CHAINS /   9 HYP OPENED

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

Details

Positions

...973.48.83..4...7...2.....7...15.......9.....9.38.2........5.8.1.....6.52.1...3 initial
...973.48.831.4...7..82.....7...15.......9.....9.38.2...7.8..5.8.1.9..76.52.17..3 autosolve
265973148983154762714826935376241589528769314149538627697382451831495276452617893 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (14)
C1: 5,6
C3: 4,6
E2: 5,6
F3: 5,6
H2: 6,9
D4: 2,6
E4: 4,6
I4: 4,9
B8: 3,4
F7: 2,6
F8: 2,5
D9: 4,6
G8: 2,4
H9: 8,9

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
G7,I7: 1.. / G7 = 1  => 15 pairs (_) / I7 = 1  => 21 pairs (_)
H3,H5: 1.. / H3 = 1  => 16 pairs (_) / H5 = 1  => 25 pairs (_)
D4,D5: 2.. / D4 = 2  => 13 pairs (_) / D5 = 2  =>  0 pairs (X)
F7,F8: 2.. / F7 = 2  => 16 pairs (_) / F8 = 2  =>  0 pairs (X)
A4,D4: 2.. / A4 = 2  =>  0 pairs (X) / D4 = 2  => 13 pairs (_)
F8,G8: 2.. / F8 = 2  =>  0 pairs (X) / G8 = 2  => 16 pairs (_)
B1,B5: 2.. / B1 = 2  => 17 pairs (_) / B5 = 2  => 14 pairs (_)
I2,I7: 2.. / I2 = 2  => 16 pairs (_) / I7 = 2  =>  0 pairs (X)
G3,H3: 3.. / G3 = 3  => 14 pairs (_) / H3 = 3  =>  0 pairs (*)
D7,D8: 3.. / D7 = 3  => 14 pairs (_) / D8 = 3  => 22 pairs (_)
A4,H4: 3.. / A4 = 3  => 15 pairs (_) / H4 = 3  => 14 pairs (_)
B8,D8: 3.. / B8 = 3  => 14 pairs (_) / D8 = 3  => 22 pairs (_)
G3,G5: 3.. / G3 = 3  => 14 pairs (_) / G5 = 3  =>  0 pairs (*)
B3,C3: 4.. / B3 = 4  =>  0 pairs (X) / C3 = 4  => 14 pairs (_)
E4,E5: 4.. / E4 = 4  => 15 pairs (_) / E5 = 4  => 17 pairs (_)
A1,C1: 5.. / A1 = 5  =>  0 pairs (X) / C1 = 5  => 13 pairs (_)
E2,F3: 5.. / E2 = 5  => 16 pairs (_) / F3 = 5  =>  0 pairs (X)
I2,I3: 5.. / I2 = 5  =>  0 pairs (X) / I3 = 5  => 16 pairs (_)
D8,F8: 5.. / D8 = 5  =>  0 pairs (X) / F8 = 5  => 16 pairs (_)
E2,I2: 5.. / E2 = 5  => 16 pairs (_) / I2 = 5  =>  0 pairs (X)
F3,I3: 5.. / F3 = 5  =>  0 pairs (X) / I3 = 5  => 16 pairs (_)
A6,D6: 5.. / A6 = 5  => 14 pairs (_) / D6 = 5  => 18 pairs (_)
C1,C5: 5.. / C1 = 5  => 13 pairs (_) / C5 = 5  =>  0 pairs (X)
E2,E5: 5.. / E2 = 5  => 16 pairs (_) / E5 = 5  =>  0 pairs (X)
F3,F8: 5.. / F3 = 5  =>  0 pairs (X) / F8 = 5  => 16 pairs (_)
E2,F3: 6.. / E2 = 6  =>  0 pairs (X) / F3 = 6  => 16 pairs (_)
A9,D9: 6.. / A9 = 6  => 17 pairs (_) / D9 = 6  => 17 pairs (_)
F3,F7: 6.. / F3 = 6  => 16 pairs (_) / F7 = 6  =>  0 pairs (X)
G2,I2: 7.. / G2 = 7  => 14 pairs (_) / I2 = 7  =>  0 pairs (X)
D5,D6: 7.. / D5 = 7  => 15 pairs (_) / D6 = 7  => 14 pairs (_)
C4,C5: 8.. / C4 = 8  => 14 pairs (_) / C5 = 8  =>  0 pairs (*)
G9,H9: 8.. / G9 = 8  =>  0 pairs (*) / H9 = 8  =>  0 pairs (X)
C4,H4: 8.. / C4 = 8  => 14 pairs (_) / H4 = 8  =>  0 pairs (*)
G5,G9: 8.. / G5 = 8  => 14 pairs (_) / G9 = 8  =>  0 pairs (*)
A2,B3: 9.. / A2 = 9  =>  0 pairs (*) / B3 = 9  =>  0 pairs (X)
H4,I4: 9.. / H4 = 9  =>  0 pairs (X) / I4 = 9  => 14 pairs (_)
B3,B7: 9.. / B3 = 9  => 17 pairs (_) / B7 = 9  =>  0 pairs (*)
* DURATION: 0:00:42.230726  START: 23:18:28.134267  END: 23:19:10.364993 2019-04-30
* CP COUNT: (37)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (B8,C1,C3,D4,D9,E2,E4,F3,F7,F8,G8,H2,H9,I4)
* ...973.48.831.4...7..82.....7...15.......9.....9.38.2...7.8..5.8.1.9..76.52.17..3
* PAIR C1: 5,6 BLK 1
A1: 5,6,1,2                              # reduction candidate for 5,6
A1: 5,6                                  # 20 pairs
A1: 1,2                                  # 14 pairs
* PAIR C1: 5,6 COL C
C5: 5,6,4,8                              # reduction candidate for 5,6
C5: 5,6                                  # 14 pairs
C5: 4,8                                  # 14 pairs
* PAIR C3: 4,6 BLK 1
B3: 4,6,1,9                              # reduction candidate for 4,6
B3: 4,6 => CTR
* ...973.489831.4.6.7..826..5.7...15.......9.....9.38.2..97.82.5.8.1.95276.52.17..3
B3: 1,9                                  # 15 pairs
* PAIR C3: 4,6 COL C
C4: 4,6,8                                # reduction candidate for 4,6
C4: 4,6 => SOLVED
* 265973148983154762714826935376241589528769314149538627697382451831495276452617893
C4: 8                                    # 14 pairs
C5: 4,6,5,8                              # reduction candidate for 4,6
C5: 4,6                                  # 14 pairs
* PAIR E2: 5,6 COL E
E5: 5,6,4                                # reduction candidate for 5,6
E5: 4                                    # 17 pairs
E5: 5,6                                  # 15 pairs
* PAIR H2: 6,9 BLK 3
G2: 6,9,2,7                              # reduction candidate for 6,9
G2: 6,9 => CTR
* ...973.48.831.4..77..82...5.7...15.......9.....9.38.2...7.8..528.1.9..76.52.17..3
G2: 2,7                                  # 15 pairs
G3: 6,9,1,3                              # reduction candidate for 6,9
G3: 6,9 => SOLVED
* 265973148983154762714826935376241589528769314149538627697382451831495276452617893
G3: 1,3                                  # 15 pairs
H3: 6,9,1,3                              # reduction candidate for 6,9
H3: 6,9                                  # 24 pairs
* PAIR H2: 6,9 ROW 2
A2: 6,9,2                                # reduction candidate for 6,9
A2: 2 => CTR
* 165973248283164.95794825..1.7.2415.942..59317519738624.47.86152831592476652417..3
A2: 6,9                                  # 16 pairs
* PAIR H2: 6,9 COL H
H4: 6,9,3,8                              # reduction candidate for 6,9
H4: 6,9                                  # 16 pairs
H4: 3,8                                  # 15 pairs
* PAIR D4: 2,6 BLK 5
D5: 2,6,5,7                              # reduction candidate for 2,6
D5: 2,6 => CTR
* 16597324828316479579482536137..415.9....59.17519738624947386152831592476652417983
D5: 5,7                                  # 14 pairs
* PAIR D4: 2,6 ROW 4
A4: 2,6,3,4                              # reduction candidate for 2,6
A4: 2,6                                  # 15 pairs
A4: 3,4                                  # 14 pairs
* PAIR E4: 4,6 BLK 5
E5: 4,6,5                                # reduction candidate for 4,6
E5: 5 => CTR
* 165973248283164795794825..1378241569....59.1.519.38.24..7386152831592476652417983
E5: 4,6                                  # 16 pairs
* PAIR E4: 4,6 ROW 4
A4: 4,6,2,3                              # reduction candidate for 4,6
A4: 4,6                                  # 19 pairs
C4: 4,6,8                                # reduction candidate for 4,6
C4: 4,6 => SOLVED
* 265973148983154762714826935376241589528769314149538627697382451831495276452617893
C4: 8                                    # 14 pairs
* PAIR I4: 4,9 COL I
I7: 4,9,1,2                              # reduction candidate for 4,9
I7: 4,9 => CTR
* ..5973648683154792794826315.78..15.9..6.4983..19.3842.9.7.821548.1.95276.52.17983
I7: 1,2                                  # 15 pairs
* PAIR B8: 3,4 BLK 7
A7: 3,4,6,9                              # reduction candidate for 3,4
A7: 3,4                                  # 17 pairs
B7: 3,4,6,9                              # reduction candidate for 3,4
B7: 3,4 => CTR
* 165973248283164.95794825..1.7.2415.942..59317519738624.47.86152831592476652417..3
B7: 6,9                                  # 15 pairs
* PAIR B8: 3,4 ROW 8
D8: 3,4,5                                # reduction candidate for 3,4
D8: 5 => CTR
* 165973248283164795794825..1378241569....59.1.519.38.24947386152831592476652417983
D8: 3,4                                  # 16 pairs
* PAIR B8: 3,4 COL B
B5: 3,4,1,2,6                            # reduction candidate for 3,4
B5: 3,4                                  # 24 pairs
B5: 1,2,6                                # 14 pairs
* PAIR D9: 4,6 BLK 8
D7: 4,6,3                                # reduction candidate for 4,6
D7: 4,6                                  # 22 pairs
D7: 3                                    # 14 pairs
* PAIR D9: 4,6 ROW 9
A9: 4,6,9                                # reduction candidate for 4,6
A9: 9 => CTR
* ...973648683154792794826315.782.15.9..6.4983...9.38124..7.82.5.8.1.95276952617483
A9: 4,6                                  # 16 pairs
* PAIR G8: 2,4 BLK 9
G7: 2,4,1,9                              # reduction candidate for 2,4
G7: 2,4                                  # 23 pairs
I7: 2,4,1,9                              # reduction candidate for 2,4
I7: 2,4                                  # 18 pairs
* PAIR H9: 8,9 BLK 9
G9: 8,9,4                                # reduction candidate for 8,9
G9: 4 => CTR
* ...973648683154792794826315.782.15.9..6.4983...9.38124..7.82.5.8.1.95276952617483
G9: 8,9                                  # 16 pairs
* PAIR H9: 8,9 COL H
H4: 8,9,3,6                              # reduction candidate for 8,9
H4: 8,9 => SOLVED
* 265973148983154762714826935376241589528769314149538627697382451831495276452617893
H4: 3,6                                  # 15 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060521-absurd-base-pr-000.dot
* REASONING
* DIS # B3: 4,6 => CTR => B3: 1,9
* PRF # C4: 4,6 => SOL
* DIS # G2: 6,9 => CTR => G2: 2,7
* PRF # G3: 6,9 => SOL
* DIS # A2: 2 => CTR => A2: 6,9
* DIS # D5: 2,6 => CTR => D5: 5,7
* DIS # E5: 5 => CTR => E5: 4,6
* PRF # C4: 4,6 => SOL
* DIS # I7: 4,9 => CTR => I7: 1,2
* DIS # B7: 3,4 => CTR => B7: 6,9
* DIS # D8: 5 => CTR => D8: 3,4
* DIS # A9: 9 => CTR => A9: 4,6
* DIS # G9: 4 => CTR => G9: 8,9
* PRF # H4: 8,9 => SOL
* CNT  14 HDP CHAINS /  48 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (B8,C1,C3,D4,D9,E2,E4,F3,F7,F8,G8,H2,H9,I4)
* ...973.48.831.4...7..82.....7...15.......9.....9.38.2...7.8..5.8.1.9..76.52.17..3
* PAIR C1: 5,6 BLK 1
A1: 5,6,1,2                              # reduction candidate for 5,6
A1: 5,6                                  # 20 pairs
A1: 1,2                                  # 14 pairs
* PAIR C1: 5,6 COL C
C5: 5,6,4,8                              # reduction candidate for 5,6
C5: 5,6                                  # 14 pairs
C5: 4,8                                  # 14 pairs
* PAIR C3: 4,6 BLK 1
B3: 4,6,1,9                              # reduction candidate for 4,6
B3: 4,6 => CTR
* ...973.489831.4.6.7..826..5.7...15.......9.....9.38.2..97.82.5.8.1.95276.52.17..3
* PAIR E2: 5,6 COL E
E5: 5,6,4                                # reduction candidate for 5,6
E5: 4                                    # 17 pairs
E5: 5,6                                  # 15 pairs
* PAIR H2: 6,9 BLK 3
G2: 6,9,2,7                              # reduction candidate for 6,9
G2: 6,9 => CTR
* ...973.48.831.4..77.482...5.7...15.......9.....9.38.2...7.8..528.1.9..76.52.17..3
G3: 6,9,1,3                              # reduction candidate for 6,9
G3: 6,9 => SOLVED
* 265973148983154762714826935376241589528769314149538627697382451831495276452617893
* DURATION: 0:00:06.283609  START: 23:19:39.028462  END: 23:19:45.312071 2019-04-30
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060521-absurd-base-pr-001.dot
* REASONING
* DIS # B3: 4,6 => CTR => B3: 1,9
* DIS B3: 1,9 # G2: 6,9 => CTR => G2: 2,7
* PRF B3: 1,9 + G2: 2,7 # G3: 6,9 => SOL
* STA B3: 1,9 + G2: 2,7 + G3: 6,9
* CNT   3 HDP CHAINS /   9 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=May&YEAR=2006, 20060521, absurd

Solution

position: 265973148983154762714826935376241589528769314149538627697382451831495276452617893 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: 5,6 => UNS
* INC # A1: 1,2 => UNS
* INC # C5: 5,6 => UNS
* INC # C5: 4,8 => UNS
* DIS # B3: 4,6 => CTR => B3: 1,9
* INC # B3: 1,9 => UNS
* PRF # C4: 4,6 => SOL
* INC # C4: 8 => UNS
* INC # C5: 4,6 => UNS
* INC # E5: 5,6 => UNS
* INC # E5: 4 => UNS
* DIS # G2: 6,9 => CTR => G2: 2,7
* INC # G2: 2,7 => UNS
* PRF # G3: 6,9 => SOL
* INC # G3: 1,3 => UNS
* INC # H3: 6,9 => UNS
* INC # A2: 6,9 => UNS
* DIS # A2: 2 => CTR => A2: 6,9
* INC # H4: 6,9 => UNS
* INC # H4: 3,8 => UNS
* DIS # D5: 2,6 => CTR => D5: 5,7
* INC # D5: 5,7 => UNS
* INC # A4: 2,6 => UNS
* INC # A4: 3,4 => UNS
* INC # E5: 4,6 => UNS
* DIS # E5: 5 => CTR => E5: 4,6
* INC # A4: 4,6 => UNS
* PRF # C4: 4,6 => SOL
* INC # C4: 8 => UNS
* DIS # I7: 4,9 => CTR => I7: 1,2
* INC # I7: 1,2 => UNS
* INC # A7: 3,4 => UNS
* DIS # B7: 3,4 => CTR => B7: 6,9
* INC # B7: 6,9 => UNS
* INC # D8: 3,4 => UNS
* DIS # D8: 5 => CTR => D8: 3,4
* INC # B5: 3,4 => UNS
* INC # B5: 1,2,6 => UNS
* INC # D7: 4,6 => UNS
* INC # D7: 3 => UNS
* INC # A9: 4,6 => UNS
* DIS # A9: 9 => CTR => A9: 4,6
* INC # G7: 2,4 => UNS
* INC # I7: 2,4 => UNS
* INC # G9: 8,9 => UNS
* DIS # G9: 4 => CTR => G9: 8,9
* PRF # H4: 8,9 => SOL
* INC # H4: 3,6 => UNS
* CNT  48 HDP CHAINS /  48 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # A1: 5,6 => UNS
* INC # A1: 1,2 => UNS
* INC # C5: 5,6 => UNS
* INC # C5: 4,8 => UNS
* DIS # B3: 4,6 => CTR => B3: 1,9
* INC B3: 1,9 # E5: 5,6 => UNS
* INC B3: 1,9 # E5: 4 => UNS
* DIS B3: 1,9 # G2: 6,9 => CTR => G2: 2,7
* PRF B3: 1,9 + G2: 2,7 # G3: 6,9 => SOL
* STA B3: 1,9 + G2: 2,7 + G3: 6,9
* CNT   9 HDP CHAINS /   9 HYP OPENED