Analysis of zz-www.sudokuoftheday.co.uk-20060902-absurd-base.sdk

Contents

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

level: medium

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

position: ..6....74......1....81....25..69...7..9..23.........4.1.3..8.257...56..19..4..... initial

Autosolve

position: .16....74......1....81....25..69...78.9..23.66......491.3978.257...56..19..4..7.. autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # F3: 3,4 => CTR => F3: 5,7,9
* DIS # E2: 3,8 => CTR => E2: 2,4,6
* PRF # D6: 5,7 => SOL
* DIS # F4: 3 => CTR => F4: 1,4
* DIS # C4: 1 => CTR => C4: 2,4
* DIS # B9: 2,5 => CTR => B9: 6,8
* DIS # E9: 1 => CTR => E9: 2,3
* DIS # E9: 1,3 => CTR => E9: 2
* DIS # F4: 1,3 => CTR => F4: 4
* PRF # F4: 4 => SOL
* PRF # F6: 1,3 => SOL
* DIS # H9: 3,8 => CTR => H9: 6
* CNT  12 HDP CHAINS /  44 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 # F3: 3,4 => CTR => F3: 5,7,9
* DIS F3: 5,7,9 # E3: 6 => CTR => E3: 3,4
* DIS F3: 5,7,9 + E3: 3,4 # H2: 5,9 => CTR => H2: 3,8
* PRF F3: 5,7,9 + E3: 3,4 + H2: 3,8 # D6: 5,7 => SOL
* STA F3: 5,7,9 + E3: 3,4 + H2: 3,8 + D6: 5,7
* CNT   4 HDP CHAINS /  17 HYP OPENED

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

Details

Positions

..6....74......1....81....25..69...7..9..23.........4.1.3..8.257...56..19..4..... initial
.16....74......1....81....25..69...78.9..23.66......491.3978.257...56..19..4..7.. autosolve
216839574497265138358147692532694817849712356671583249163978425724356981985421763 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (18)
A1: 2,3
C2: 5,7
A3: 3,4
I2: 3,8
B5: 4,7
D5: 5,7
E5: 1,4
G4: 2,8
H4: 1,8
H5: 1,5
G6: 2,5
B7: 4,6
C8: 2,4
C9: 2,5
D8: 2,3
F9: 1,3
G7: 4,6
I9: 3,8

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
C4,C6: 1.. / C4 = 1  =>  0 pairs (X) / C6 = 1  => 23 pairs (_)
H4,H5: 1.. / H4 = 1  =>  0 pairs (*) / H5 = 1  =>  0 pairs (X)
E9,F9: 1.. / E9 = 1  =>  0 pairs (X) / F9 = 1  => 19 pairs (_)
E5,H5: 1.. / E5 = 1  =>  0 pairs (*) / H5 = 1  =>  0 pairs (X)
A1,A2: 2.. / A1 = 2  => 20 pairs (_) / A2 = 2  => 19 pairs (_)
G4,G6: 2.. / G4 = 2  =>  0 pairs (X) / G6 = 2  =>  0 pairs (_)
D8,E9: 2.. / D8 = 2  =>  0 pairs (X) / E9 = 2  => 22 pairs (_)
B4,B6: 3.. / B4 = 3  => 23 pairs (_) / B6 = 3  =>  0 pairs (X)
B4,F4: 3.. / B4 = 3  => 23 pairs (_) / F4 = 3  =>  0 pairs (X)
D8,H8: 3.. / D8 = 3  => 22 pairs (_) / H8 = 3  =>  0 pairs (X)
I2,I9: 3.. / I2 = 3  => 20 pairs (_) / I9 = 3  => 23 pairs (_)
A2,A3: 4.. / A2 = 4  => 19 pairs (_) / A3 = 4  => 19 pairs (_)
F4,E5: 4.. / F4 = 4  =>  0 pairs (*) / E5 = 4  =>  0 pairs (X)
G7,G8: 4.. / G7 = 4  => 20 pairs (_) / G8 = 4  =>  0 pairs (X)
B5,E5: 4.. / B5 = 4  =>  0 pairs (*) / E5 = 4  =>  0 pairs (X)
B7,G7: 4.. / B7 = 4  =>  0 pairs (X) / G7 = 4  => 20 pairs (_)
C4,C8: 4.. / C4 = 4  =>  0 pairs (X) / C8 = 4  => 23 pairs (_)
H5,G6: 5.. / H5 = 5  =>  0 pairs (*) / G6 = 5  =>  0 pairs (X)
B9,C9: 5.. / B9 = 5  =>  0 pairs (X) / C9 = 5  => 19 pairs (_)
D5,H5: 5.. / D5 = 5  =>  0 pairs (X) / H5 = 5  =>  0 pairs (_)
C2,C9: 5.. / C2 = 5  =>  0 pairs (X) / C9 = 5  => 19 pairs (_)
E2,E3: 6.. / E2 = 6  => 20 pairs (_) / E3 = 6  =>  0 pairs (X)
B7,B9: 6.. / B7 = 6  => 20 pairs (_) / B9 = 6  =>  0 pairs (X)
G7,H9: 6.. / G7 = 6  =>  0 pairs (X) / H9 = 6  => 20 pairs (_)
E2,H2: 6.. / E2 = 6  => 20 pairs (_) / H2 = 6  =>  0 pairs (X)
B7,G7: 6.. / B7 = 6  => 20 pairs (_) / G7 = 6  =>  0 pairs (X)
B9,H9: 6.. / B9 = 6  =>  0 pairs (X) / H9 = 6  => 20 pairs (_)
G3,G7: 6.. / G3 = 6  => 20 pairs (_) / G7 = 6  =>  0 pairs (X)
B3,F3: 7.. / B3 = 7  =>  0 pairs (X) / F3 = 7  => 19 pairs (_)
B5,D5: 7.. / B5 = 7  =>  0 pairs (X) / D5 = 7  =>  0 pairs (_)
C2,C6: 7.. / C2 = 7  => 19 pairs (_) / C6 = 7  =>  0 pairs (X)
D6,E6: 8.. / D6 = 8  => 20 pairs (_) / E6 = 8  => 21 pairs (_)
G4,H4: 8.. / G4 = 8  =>  0 pairs (*) / H4 = 8  =>  0 pairs (X)
B8,B9: 8.. / B8 = 8  => 20 pairs (_) / B9 = 8  => 24 pairs (_)
I2,I9: 8.. / I2 = 8  => 23 pairs (_) / I9 = 8  => 20 pairs (_)
B2,B3: 9.. / B2 = 9  => 19 pairs (_) / B3 = 9  => 21 pairs (_)
G8,H8: 9.. / G8 = 9  => 22 pairs (_) / H8 = 9  => 22 pairs (_)
F1,G1: 9.. / F1 = 9  => 19 pairs (_) / G1 = 9  =>  0 pairs (X)
* DURATION: 0:00:43.732563  START: 02:17:58.679235  END: 02:18:42.411798 2019-05-01
* CP COUNT: (38)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A1,A3,B5,B7,C2,C8,C9,D5,D8,E5,F9,G4,G6,G7,H4,H5,I2,I9)
* .16....74......1....81....25..69...78.9..23.66......491.3978.257...56..19..4..7..
* PAIR A1: 2,3 BLK 1
A2: 2,3,4                                # reduction candidate for 2,3
A2: 4                                    # 19 pairs
A2: 2,3                                  # 19 pairs
* PAIR A1: 2,3 ROW 1
D1: 2,3,5,8                              # reduction candidate for 2,3
D1: 2,3                                  # 26 pairs
E1: 2,3,8                                # reduction candidate for 2,3
E1: 2,3                                  # 21 pairs
* PAIR C2: 5,7 BLK 1
B2: 5,7,9                                # reduction candidate for 5,7
B2: 5,7                                  # 21 pairs
B3: 5,7,9                                # reduction candidate for 5,7
B3: 5,7                                  # 19 pairs
* PAIR C2: 5,7 ROW 2
D2: 5,7,2,3,8                            # reduction candidate for 5,7
D2: 5,7                                  # 25 pairs
F2: 5,7,3,4,9                            # reduction candidate for 5,7
F2: 5,7                                  # 20 pairs
* PAIR A3: 3,4 BLK 1
A2: 3,4,2                                # reduction candidate for 3,4
A2: 3,4                                  # 20 pairs
A2: 2                                    # 19 pairs
* PAIR A3: 3,4 ROW 3
E3: 3,4,6                                # reduction candidate for 3,4
E3: 3,4                                  # 20 pairs
F3: 3,4,5,7,9                            # reduction candidate for 3,4
F3: 3,4 => CTR
* .16....74......1...781....25..69...78497123566......491.3978.257...56..19..4..7..
F3: 5,7,9                                # 18 pairs
* PAIR I2: 3,8 BLK 3
H2: 3,8,5,6,9                            # reduction candidate for 3,8
H2: 3,8                                  # 22 pairs
H2: 5,6,9                                # 18 pairs
* PAIR I2: 3,8 ROW 2
D2: 3,8,2,5,7                            # reduction candidate for 3,8
D2: 3,8                                  # 20 pairs
E2: 3,8,2,4,6                            # reduction candidate for 3,8
E2: 3,8 => CTR
* .16....74......16...816...25..69...78.9.423166.....5491.39786257...564919654217..
E2: 2,4,6                                # 18 pairs
* PAIR D5: 5,7 BLK 5
D6: 5,7,3,8                              # reduction candidate for 5,7
D6: 5,7 => SOLVED
* 216839574497265138358147692532694817849712356671583249163978425724356981985421763
D6: 3,8                                  # 20 pairs
F6: 5,7,1,3                              # reduction candidate for 5,7
F6: 5,7                                  # 20 pairs
* PAIR D5: 5,7 COL D
D2: 5,7,2,3,8                            # reduction candidate for 5,7
D2: 5,7                                  # 25 pairs
D2: 2,3,8                                # 18 pairs
* PAIR E5: 1,4 BLK 5
F4: 1,4,3                                # reduction candidate for 1,4
F4: 3 => CTR
* .16....74......1....81....25.1693287879542316632.175491.3978.257.4.56..19.54.17..
F4: 1,4                                  # 23 pairs
* PAIR C8: 2,4 BLK 7
B8: 2,4,8                                # reduction candidate for 2,4
B8: 2,4                                  # 24 pairs
B8: 8                                    # 20 pairs
* PAIR C8: 2,4 COL C
C4: 2,4,1                                # reduction candidate for 2,4
C4: 1 => CTR
* 316285974257.6.1.8..813.652541693287879542316632...5491639784257.4356891985421763
C4: 2,4                                  # 23 pairs
* PAIR C9: 2,5 BLK 7
B9: 2,5,6,8                              # reduction candidate for 2,5
B9: 2,5 => CTR
* .16.29.742...641.34.813.6.254.693..787954231663..81.491639784257842569319..4..768
B9: 6,8                                  # 22 pairs
* PAIR D8: 2,3 BLK 8
E9: 2,3,1                                # reduction candidate for 2,3
E9: 1 => CTR
* .16....74......1.3..81....253.69...78.9.423166.....5491.3978.257842569319..413768
E9: 2,3                                  # 19 pairs
* PAIR D8: 2,3 COL D
D1: 2,3,5,8                              # reduction candidate for 2,3
D1: 2,3                                  # 26 pairs
D2: 2,3,5,7,8                            # reduction candidate for 2,3
D2: 2,3                                  # 20 pairs
* PAIR F9: 1,3 BLK 8
E9: 1,3,2                                # reduction candidate for 1,3
E9: 1,3 => CTR
* .16.29.742...641.34.813.6.254.693..787954231663..81.491639784257842569319..4..768
E9: 2                                    # 22 pairs
* PAIR F9: 1,3 COL F
F4: 1,3,4                                # reduction candidate for 1,3
F4: 1,3 => CTR
* .16..5974..7...1.8..81.76.25..69.2878795423166..78.5491639784257...568919854..7..
F4: 4 => SOLVED
* 216839574497265138358147692532694817849712356671583249163978425724356981985421763
F6: 1,3,5,7                              # reduction candidate for 1,3
F6: 1,3 => SOLVED
* 216839574497265138358147692532694817849712356671583249163978425724356981985421763
F6: 5,7                                  # 20 pairs
* PAIR I9: 3,8 BLK 9
H8: 3,8,9                                # reduction candidate for 3,8
H8: 3,8                                  # 22 pairs
H9: 3,8,6                                # reduction candidate for 3,8
H9: 3,8 => CTR
* .16....74..7...1....81.7..25.4693.17879..23.66......491.39786257...564919654217..
H9: 6                                    # 20 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060902-absurd-base-pr-000.dot
* REASONING
* DIS # F3: 3,4 => CTR => F3: 5,7,9
* DIS # E2: 3,8 => CTR => E2: 2,4,6
* PRF # D6: 5,7 => SOL
* DIS # F4: 3 => CTR => F4: 1,4
* DIS # C4: 1 => CTR => C4: 2,4
* DIS # B9: 2,5 => CTR => B9: 6,8
* DIS # E9: 1 => CTR => E9: 2,3
* DIS # E9: 1,3 => CTR => E9: 2
* DIS # F4: 1,3 => CTR => F4: 4
* PRF # F4: 4 => SOL
* PRF # F6: 1,3 => SOL
* DIS # H9: 3,8 => CTR => H9: 6
* CNT  12 HDP CHAINS /  44 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A1,A3,B5,B7,C2,C8,C9,D5,D8,E5,F9,G4,G6,G7,H4,H5,I2,I9)
* .16....74......1....81....25..69...78.9..23.66......491.3978.257...56..19..4..7..
* PAIR A1: 2,3 BLK 1
A2: 2,3,4                                # reduction candidate for 2,3
A2: 4                                    # 19 pairs
A2: 2,3                                  # 19 pairs
* PAIR A1: 2,3 ROW 1
D1: 2,3,5,8                              # reduction candidate for 2,3
D1: 2,3                                  # 26 pairs
E1: 2,3,8                                # reduction candidate for 2,3
E1: 2,3                                  # 21 pairs
* PAIR C2: 5,7 BLK 1
B2: 5,7,9                                # reduction candidate for 5,7
B2: 5,7                                  # 21 pairs
B3: 5,7,9                                # reduction candidate for 5,7
B3: 5,7                                  # 19 pairs
* PAIR C2: 5,7 ROW 2
D2: 5,7,2,3,8                            # reduction candidate for 5,7
D2: 5,7                                  # 25 pairs
F2: 5,7,3,4,9                            # reduction candidate for 5,7
F2: 5,7                                  # 20 pairs
* PAIR A3: 3,4 BLK 1
A2: 3,4,2                                # reduction candidate for 3,4
A2: 3,4                                  # 20 pairs
A2: 2                                    # 19 pairs
* PAIR A3: 3,4 ROW 3
E3: 3,4,6                                # reduction candidate for 3,4
E3: 3,4                                  # 20 pairs
F3: 3,4,5,7,9                            # reduction candidate for 3,4
F3: 3,4 => CTR
* .16....74......1...781....25..69...78497123566......491.3978.257...56..19..4..7..
* RESTART
* PAIR A3: 3,4 ROW 3
E3: 3,4,6                                # reduction candidate for 3,4
E3: 6 => CTR
* .16....74..7...1684.8167.325.4693817879..23.66......491.39786257..356491965421783
* PAIR RESTART
* PAIR I2: 3,8 BLK 3
H2: 3,8,5,9                              # reduction candidate for 3,8
H2: 5,9 => CTR
* .16.298742..8641.34.81....25..69.2878.9..23166...8.5491.3978.2578..56..19..413768
* PAIR D5: 5,7 BLK 5
D6: 5,7,3,8                              # reduction candidate for 5,7
D6: 5,7 => SOLVED
* 216839574497265138358147692532694817849712356671583249163978425724356981985421763
* DURATION: 0:00:11.393258  START: 02:19:10.953092  END: 02:19:22.346350 2019-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060902-absurd-base-pr-001.dot
* REASONING
* DIS # F3: 3,4 => CTR => F3: 5,7,9
* DIS F3: 5,7,9 # E3: 6 => CTR => E3: 3,4
* DIS F3: 5,7,9 + E3: 3,4 # H2: 5,9 => CTR => H2: 3,8
* PRF F3: 5,7,9 + E3: 3,4 + H2: 3,8 # D6: 5,7 => SOL
* STA F3: 5,7,9 + E3: 3,4 + H2: 3,8 + D6: 5,7
* CNT   4 HDP CHAINS /  17 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Sep&YEAR=2006, 20060902, absurd

Solution

position: 216839574497265138358147692532694817849712356671583249163978425724356981985421763 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 # A2: 2,3 => UNS
* INC # A2: 4 => UNS
* INC # D1: 2,3 => UNS
* INC # E1: 2,3 => UNS
* INC # B2: 5,7 => UNS
* INC # B3: 5,7 => UNS
* INC # D2: 5,7 => UNS
* INC # F2: 5,7 => UNS
* INC # A2: 3,4 => UNS
* INC # A2: 2 => UNS
* INC # E3: 3,4 => UNS
* DIS # F3: 3,4 => CTR => F3: 5,7,9
* INC # F3: 5,7,9 => UNS
* INC # H2: 3,8 => UNS
* INC # H2: 5,6,9 => UNS
* INC # D2: 3,8 => UNS
* DIS # E2: 3,8 => CTR => E2: 2,4,6
* INC # E2: 2,4,6 => UNS
* PRF # D6: 5,7 => SOL
* INC # D6: 3,8 => UNS
* INC # F6: 5,7 => UNS
* INC # D2: 5,7 => UNS
* INC # D2: 2,3,8 => UNS
* INC # F4: 1,4 => UNS
* DIS # F4: 3 => CTR => F4: 1,4
* INC # B8: 2,4 => UNS
* INC # B8: 8 => UNS
* INC # C4: 2,4 => UNS
* DIS # C4: 1 => CTR => C4: 2,4
* DIS # B9: 2,5 => CTR => B9: 6,8
* INC # B9: 6,8 => UNS
* INC # E9: 2,3 => UNS
* DIS # E9: 1 => CTR => E9: 2,3
* INC # D1: 2,3 => UNS
* INC # D2: 2,3 => UNS
* DIS # E9: 1,3 => CTR => E9: 2
* INC # E9: 2 => UNS
* DIS # F4: 1,3 => CTR => F4: 4
* PRF # F4: 4 => SOL
* PRF # F6: 1,3 => SOL
* INC # F6: 5,7 => UNS
* INC # H8: 3,8 => UNS
* DIS # H9: 3,8 => CTR => H9: 6
* INC # H9: 6 => UNS
* CNT  44 HDP CHAINS /  44 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # A2: 2,3 => UNS
* INC # A2: 4 => UNS
* INC # D1: 2,3 => UNS
* INC # E1: 2,3 => UNS
* INC # B2: 5,7 => UNS
* INC # B3: 5,7 => UNS
* INC # D2: 5,7 => UNS
* INC # F2: 5,7 => UNS
* INC # A2: 3,4 => UNS
* INC # A2: 2 => UNS
* INC # E3: 3,4 => UNS
* DIS # F3: 3,4 => CTR => F3: 5,7,9
* INC F3: 5,7,9 # E3: 3,4 => UNS
* DIS F3: 5,7,9 # E3: 6 => CTR => E3: 3,4
* INC F3: 5,7,9 + E3: 3,4 # H2: 3,8 => UNS
* DIS F3: 5,7,9 + E3: 3,4 # H2: 5,9 => CTR => H2: 3,8
* PRF F3: 5,7,9 + E3: 3,4 + H2: 3,8 # D6: 5,7 => SOL
* STA F3: 5,7,9 + E3: 3,4 + H2: 3,8 + D6: 5,7
* CNT  17 HDP CHAINS /  17 HYP OPENED