Analysis of zz-www.sudokuoftheday.co.uk-20060612-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.......4..7..43959...1..7.29..3.........5.8956....2.......74..7...6...8.5...3.6. initial

Autosolve

position: 3....9..4..7..439594531..7.29..3.....73..5.8956....2.......74..7...6...8.5...3.6. autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* PRF # B2: 2,8 => SOL
* DIS # B2: 1 => CTR => B2: 2,8
* DIS # B7: 2,8 => CTR => B7: 1,3
* PRF # C7: 1,9 => SOL
* DIS # D2: 2,8 => CTR => D2: 6
* PRF # D2: 6 => SOL
* PRF # F3: 2,8 => SOL
* DIS # F3: 6 => CTR => F3: 2,8
* PRF # B2: 2,8 => SOL
* DIS # B2: 1 => CTR => B2: 2,8
* DIS # E7: 2,8 => CTR => E7: 5,9
* DIS # E9: 2,8 => CTR => E9: 4,9
* DIS # G1: 6,8 => CTR => G1: 1
* PRF # G1: 1 => SOL
* DIS # F3: 6,8 => CTR => F3: 2
* PRF # F3: 2 => SOL
* DIS # F3: 8 => CTR => F3: 2,6
* DIS # C4: 1,4 => CTR => C4: 8
* PRF # D5: 1,4 => SOL
* DIS # A9: 1,4 => CTR => A9: 8
* DIS # D5: 2,4 => CTR => D5: 1,6
* DIS # D4: 1,8 => CTR => D4: 4,6,7
* DIS # F4: 1,8 => CTR => F4: 6
* PRF # F4: 6 => SOL
* DIS # D6: 1,8 => CTR => D6: 4,7,9
* DIS # C6: 4 => CTR => C6: 1,8
* PRF # I4: 7 => SOL
* DIS # D5: 2,4 => CTR => D5: 1,6
* DIS # G1: 8 => CTR => G1: 1,6
* CNT  29 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 # B2: 2,8 => SOL
* STA B2: 2,8
* CNT   1 HDP CHAINS /   1 HYP OPENED

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

Details

Positions

3.......4..7..43959...1..7.29..3.........5.8956....2.......74..7...6...8.5...3.6. initial
3....9..4..7..439594531..7.29..3.....73..5.8956....2.......74..7...6...8.5...3.6. autosolve
386579124127684395945312876298436517473125689561798243619857432734261958852943761 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (16)
B1: 2,8
C1: 2,6
D1: 5,7
E1: 5,7
E2: 2,8
H1: 1,2
G3: 6,8
I3: 2,6
A5: 1,4
E5: 2,4
F6: 1,8
G4: 5,7
G5: 1,6
F8: 1,2
G8: 5,9
G9: 7,9

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
A2,B2: 1.. / A2 = 1  =>  0 pairs (*) / B2 = 1  =>  0 pairs (X)
G1,H1: 1.. / G1 = 1  =>  0 pairs (*) / H1 = 1  =>  0 pairs (X)
G1,G5: 1.. / G1 = 1  =>  0 pairs (*) / G5 = 1  =>  0 pairs (X)
H1,I3: 2.. / H1 = 2  =>  0 pairs (*) / I3 = 2  =>  0 pairs (X)
D5,E5: 2.. / D5 = 2  =>  0 pairs (X) / E5 = 2  => 19 pairs (_)
F3,I3: 2.. / F3 = 2  =>  0 pairs (*) / I3 = 2  =>  0 pairs (X)
F3,F8: 2.. / F3 = 2  =>  0 pairs (*) / F8 = 2  =>  0 pairs (X)
H6,I6: 3.. / H6 = 3  => 16 pairs (_) / I6 = 3  => 20 pairs (_)
B7,B8: 3.. / B7 = 3  => 23 pairs (_) / B8 = 3  => 16 pairs (_)
B8,H8: 3.. / B8 = 3  => 16 pairs (_) / H8 = 3  => 23 pairs (_)
I6,I7: 3.. / I6 = 3  => 20 pairs (_) / I7 = 3  => 16 pairs (_)
H4,H6: 4.. / H4 = 4  => 16 pairs (_) / H6 = 4  => 21 pairs (_)
C8,D8: 4.. / C8 = 4  => 26 pairs (_) / D8 = 4  => 16 pairs (_)
A5,A9: 4.. / A5 = 4  => 25 pairs (_) / A9 = 4  =>  0 pairs (X)
D1,E1: 5.. / D1 = 5  => 14 pairs (_) / E1 = 5  => 15 pairs (_)
G4,H4: 5.. / G4 = 5  => 15 pairs (_) / H4 = 5  => 21 pairs (_)
E1,E7: 5.. / E1 = 5  => 15 pairs (_) / E7 = 5  => 14 pairs (_)
G4,G8: 5.. / G4 = 5  => 15 pairs (_) / G8 = 5  => 21 pairs (_)
C1,A2: 6.. / C1 = 6  =>  0 pairs (*) / A2 = 6  =>  0 pairs (X)
D2,F3: 6.. / D2 = 6  =>  0 pairs (*) / F3 = 6  =>  0 pairs (X)
I4,G5: 6.. / I4 = 6  =>  0 pairs (X) / G5 = 6  =>  0 pairs (_)
A7,C7: 6.. / A7 = 6  =>  0 pairs (*) / C7 = 6  =>  0 pairs (X)
C1,G1: 6.. / C1 = 6  =>  0 pairs (*) / G1 = 6  =>  0 pairs (X)
A2,D2: 6.. / A2 = 6  =>  0 pairs (X) / D2 = 6  =>  0 pairs (_)
D5,G5: 6.. / D5 = 6  =>  0 pairs (X) / G5 = 6  =>  0 pairs (_)
A2,A7: 6.. / A2 = 6  =>  0 pairs (X) / A7 = 6  =>  0 pairs (_)
C1,C7: 6.. / C1 = 6  =>  0 pairs (*) / C7 = 6  =>  0 pairs (X)
F3,F4: 6.. / F3 = 6  =>  0 pairs (X) / F4 = 6  =>  0 pairs (_)
I3,I4: 6.. / I3 = 6  =>  0 pairs (*) / I4 = 6  =>  0 pairs (X)
D1,E1: 7.. / D1 = 7  => 15 pairs (_) / E1 = 7  => 14 pairs (_)
G9,I9: 7.. / G9 = 7  => 15 pairs (_) / I9 = 7  => 21 pairs (_)
E1,E6: 7.. / E1 = 7  => 14 pairs (_) / E6 = 7  => 15 pairs (_)
G4,G9: 7.. / G4 = 7  => 21 pairs (_) / G9 = 7  => 15 pairs (_)
G1,G3: 8.. / G1 = 8  =>  0 pairs (X) / G3 = 8  => 18 pairs (_)
C4,C6: 8.. / C4 = 8  => 18 pairs (_) / C6 = 8  =>  0 pairs (X)
B1,G1: 8.. / B1 = 8  => 18 pairs (_) / G1 = 8  =>  0 pairs (X)
F3,G3: 8.. / F3 = 8  =>  0 pairs (X) / G3 = 8  => 18 pairs (_)
D6,E6: 9.. / D6 = 9  => 16 pairs (_) / E6 = 9  => 14 pairs (_)
G8,G9: 9.. / G8 = 9  => 15 pairs (_) / G9 = 9  => 21 pairs (_)
* DURATION: 0:00:43.373571  START: 23:47:07.056513  END: 23:47:50.430084 2019-04-30
* CP COUNT: (39)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A5,B1,C1,D1,E1,E2,E5,F6,F8,G3,G4,G5,G8,G9,H1,I3)
* 3....9..4..7..439594531..7.29..3.....73..5.8956....2.......74..7...6...8.5...3.6.
* PAIR B1: 2,8 BLK 1
B2: 2,8,1                                # reduction candidate for 2,8
B2: 2,8 => SOLVED
* 386579124127684395945312876298436517473125689561798243619857432734261958852943761
B2: 1 => CTR
* 326..9.14.17..439594531..7229..3...6.7362518956....2.......74..7...62..8.52..3.6.
* PAIR B1: 2,8 COL B
B7: 2,8,1,3                              # reduction candidate for 2,8
B7: 2,8 => CTR
* 326..9.14.17..439594531..7229..3...6.7362518956....2.......74..73..62.58.52..3.6.
B7: 1,3                                  # 18 pairs
* PAIR C1: 2,6 COL C
C7: 2,6,1,9                              # reduction candidate for 2,6
C7: 1,9 => SOLVED
* 386579124127684395945312876298436517473125689561798243619857432734261958852943761
C7: 2,6                                  # 19 pairs
* PAIR E2: 2,8 BLK 2
D2: 2,8,6                                # reduction candidate for 2,8
D2: 2,8 => CTR
* 3....9..4617..439594531687229..3...6.7362518956....2....6..74..7...62..8.52..3.6.
D2: 6 => SOLVED
* 386579124127684395945312876298436517473125689561798243619857432734261958852943761
F3: 2,8,6                                # reduction candidate for 2,8
F3: 2,8 => SOLVED
* 386579124127684395945312876298436517473125689561798243619857432734261958852943761
F3: 6 => CTR
* 3....9..4..7..439594531687229..3...6.7362518956....2.......74..7...62..8.52..3.6.
* PAIR E2: 2,8 ROW 2
B2: 2,8,1                                # reduction candidate for 2,8
B2: 2,8 => SOLVED
* 386579124127684395945312876298436517473125689561798243619857432734261958852943761
B2: 1 => CTR
* 326..9.14.17..439594531..7229..3...6.7362518956....2.......74..7...62..8.52..3.6.
* PAIR E2: 2,8 COL E
E7: 2,8,5,9                              # reduction candidate for 2,8
E7: 2,8 => CTR
* 3.6759124.2768439594531287629.136547173.4568956.97.2....9..74..7...6.9.845.89376.
E7: 5,9                                  # 17 pairs
E9: 2,8,4,9                              # reduction candidate for 2,8
E9: 2,8 => CTR
* 3.6..9124.2768439594531287629..36...17324568956....2.......74..7...6...845...3.6.
E9: 4,9                                  # 17 pairs
* PAIR H1: 1,2 COL H
H7: 1,2,3,5                              # reduction candidate for 1,2
H7: 1,2                                  # 20 pairs
H8: 1,2,3,5                              # reduction candidate for 1,2
H8: 1,2                                  # 21 pairs
* PAIR G3: 6,8 BLK 3
G1: 6,8,1                                # reduction candidate for 6,8
G1: 6,8 => CTR
* 326..9814..72.439594531..7229..3...6.7362518956....2.......74..7...62..8.52..3.6.
G1: 1 => SOLVED
* 386579124127684395945312876298436517473125689561798243619857432734261958852943761
* PAIR G3: 6,8 ROW 3
F3: 6,8,2                                # reduction candidate for 6,8
F3: 6,8 => CTR
* 326..9814..72.439594531..7229..3...6.7362518956....2.......74..7...62..8.52..3.6.
F3: 2 => SOLVED
* 386579124127684395945312876298436517473125689561798243619857432734261958852943761
* PAIR I3: 2,6 ROW 3
F3: 2,6,8                                # reduction candidate for 2,6
F3: 8 => CTR
* 3....9..4..762439594531867229..36....7324518956....2.......74..7...6...8.5...3.6.
F3: 2,6                                  # 18 pairs
* PAIR A5: 1,4 BLK 4
C4: 1,4,8                                # reduction candidate for 1,4
C4: 1,4 => CTR
* 326..9814..72.439594531..7229..3...6.73625189568..12.......742.7...62..8.52..3.6.
C4: 8                                    # 18 pairs
C6: 1,4,8                                # reduction candidate for 1,4
C6: 1,4                                  # 18 pairs
* PAIR A5: 1,4 ROW 5
D5: 1,4,2,6                              # reduction candidate for 1,4
D5: 1,4 => SOLVED
* 386579124127684395945312876298436517473125689561798243619857432734261958852943761
D5: 2,6                                  # 17 pairs
* PAIR A5: 1,4 COL A
A9: 1,4,8                                # reduction candidate for 1,4
A9: 1,4 => CTR
* 326..9.14.17..439594531..7229..3...6.7362518956....2.......74..7...62..8152..3.67
A9: 8                                    # 25 pairs
* PAIR E5: 2,4 BLK 5
D5: 2,4,1,6                              # reduction candidate for 2,4
D5: 2,4 => CTR
* 3.6..9124.2768439594531287629..36...173..568956....2.......74..7...6...8.5...3.6.
D5: 1,6                                  # 25 pairs
* PAIR E5: 2,4 COL E
E9: 2,4,8,9                              # reduction candidate for 2,4
E9: 2,4                                  # 21 pairs
E9: 8,9                                  # 17 pairs
* PAIR F6: 1,8 BLK 5
D4: 1,8,4,6,7                            # reduction candidate for 1,8
D4: 1,8 => CTR
* 3.6..91248.76.439594531..7.29..36...173..568956....2..6....74..7...6...845...3.6.
D4: 4,6,7                                # 16 pairs
F4: 1,8,6                                # reduction candidate for 1,8
F4: 1,8 => CTR
* 3....9..4..7..439594531687229..3...6.7362518956....2.......74..7...62..8.52..3.6.
F4: 6 => SOLVED
* 386579124127684395945312876298436517473125689561798243619857432734261958852943761
D6: 1,8,4,7,9                            # reduction candidate for 1,8
D6: 1,8 => CTR
* 3.65791248.7..439594531..7.29873.54.173.45689564.9.237....574.373.46.95845...376.
D6: 4,7,9                                # 16 pairs
* PAIR F6: 1,8 ROW 6
C6: 1,8,4                                # reduction candidate for 1,8
C6: 4 => CTR
* 3.6..91248.7..439594531..7.298.3....173..5689564...2.......74..7..46...845...3.6.
C6: 1,8                                  # 19 pairs
* PAIR G5: 1,6 BLK 6
I4: 1,6,7                                # reduction candidate for 1,6
I4: 7 => SOLVED
* 386579124127684395945312876298436517473125689561798243619857432734261958852943761
I4: 1,6                                  # 20 pairs
* PAIR G5: 1,6 ROW 5
D5: 1,6,2,4                              # reduction candidate for 1,6
D5: 2,4 => CTR
* 3.6..9124.2768439594531287629..36...173..568956....2.......74..7...6...8.5...3.6.
D5: 1,6                                  # 25 pairs
* PAIR G5: 1,6 COL G
G1: 1,6,8                                # reduction candidate for 1,6
G1: 8 => CTR
* 3.6..9814..76.439594531867.29..3.....73..5.8956....2.......74..7...6...8.5...3.6.
G1: 1,6                                  # 18 pairs
* PAIR F8: 1,2 BLK 8
D7: 1,2,5,8,9                            # reduction candidate for 1,2
D7: 1,2                                  # 17 pairs
D8: 1,2,4,5,9                            # reduction candidate for 1,2
D8: 1,2                                  # 27 pairs
D9: 1,2,4,8,9                            # reduction candidate for 1,2
D9: 1,2                                  # 17 pairs
* PAIR F8: 1,2 ROW 8
B8: 1,2,3                                # reduction candidate for 1,2
B8: 1,2                                  # 23 pairs
C8: 1,2,4,9                              # reduction candidate for 1,2
C8: 1,2                                  # 16 pairs
H8: 1,2,3,5                              # reduction candidate for 1,2
H8: 1,2                                  # 21 pairs
* PAIR G8: 5,9 ROW 8
D8: 5,9,1,2,4                            # reduction candidate for 5,9
D8: 5,9                                  # 27 pairs
D8: 1,2,4                                # 16 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060612-absurd-base-pr-000.dot
* REASONING
* PRF # B2: 2,8 => SOL
* DIS # B2: 1 => CTR => B2: 2,8
* DIS # B7: 2,8 => CTR => B7: 1,3
* PRF # C7: 1,9 => SOL
* DIS # D2: 2,8 => CTR => D2: 6
* PRF # D2: 6 => SOL
* PRF # F3: 2,8 => SOL
* DIS # F3: 6 => CTR => F3: 2,8
* PRF # B2: 2,8 => SOL
* DIS # B2: 1 => CTR => B2: 2,8
* DIS # E7: 2,8 => CTR => E7: 5,9
* DIS # E9: 2,8 => CTR => E9: 4,9
* DIS # G1: 6,8 => CTR => G1: 1
* PRF # G1: 1 => SOL
* DIS # F3: 6,8 => CTR => F3: 2
* PRF # F3: 2 => SOL
* DIS # F3: 8 => CTR => F3: 2,6
* DIS # C4: 1,4 => CTR => C4: 8
* PRF # D5: 1,4 => SOL
* DIS # A9: 1,4 => CTR => A9: 8
* DIS # D5: 2,4 => CTR => D5: 1,6
* DIS # D4: 1,8 => CTR => D4: 4,6,7
* DIS # F4: 1,8 => CTR => F4: 6
* PRF # F4: 6 => SOL
* DIS # D6: 1,8 => CTR => D6: 4,7,9
* DIS # C6: 4 => CTR => C6: 1,8
* PRF # I4: 7 => SOL
* DIS # D5: 2,4 => CTR => D5: 1,6
* DIS # G1: 8 => CTR => G1: 1,6
* CNT  29 HDP CHAINS /  57 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A5,B1,C1,D1,E1,E2,E5,F6,F8,G3,G4,G5,G8,G9,H1,I3)
* 3....9..4..7..439594531..7.29..3.....73..5.8956....2.......74..7...6...8.5...3.6.
* PAIR B1: 2,8 BLK 1
B2: 2,8,1                                # reduction candidate for 2,8
B2: 2,8 => SOLVED
* 386579124127684395945312876298436517473125689561798243619857432734261958852943761
* DURATION: 0:00:01.845342  START: 23:48:29.971006  END: 23:48:31.816348 2019-04-30
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060612-absurd-base-pr-001.dot
* REASONING
* PRF # B2: 2,8 => SOL
* STA B2: 2,8
* CNT   1 HDP CHAINS /   1 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Jun&YEAR=2006, 20060612, absurd

Solution

position: 386579124127684395945312876298436517473125689561798243619857432734261958852943761 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:

* PRF # B2: 2,8 => SOL
* DIS # B2: 1 => CTR => B2: 2,8
* DIS # B7: 2,8 => CTR => B7: 1,3
* INC # B7: 1,3 => UNS
* INC # C7: 2,6 => UNS
* PRF # C7: 1,9 => SOL
* DIS # D2: 2,8 => CTR => D2: 6
* PRF # D2: 6 => SOL
* PRF # F3: 2,8 => SOL
* DIS # F3: 6 => CTR => F3: 2,8
* PRF # B2: 2,8 => SOL
* DIS # B2: 1 => CTR => B2: 2,8
* DIS # E7: 2,8 => CTR => E7: 5,9
* INC # E7: 5,9 => UNS
* DIS # E9: 2,8 => CTR => E9: 4,9
* INC # E9: 4,9 => UNS
* INC # H7: 1,2 => UNS
* INC # H8: 1,2 => UNS
* DIS # G1: 6,8 => CTR => G1: 1
* PRF # G1: 1 => SOL
* DIS # F3: 6,8 => CTR => F3: 2
* PRF # F3: 2 => SOL
* INC # F3: 2,6 => UNS
* DIS # F3: 8 => CTR => F3: 2,6
* DIS # C4: 1,4 => CTR => C4: 8
* INC # C4: 8 => UNS
* INC # C6: 1,4 => UNS
* PRF # D5: 1,4 => SOL
* INC # D5: 2,6 => UNS
* DIS # A9: 1,4 => CTR => A9: 8
* INC # A9: 8 => UNS
* DIS # D5: 2,4 => CTR => D5: 1,6
* INC # D5: 1,6 => UNS
* INC # E9: 2,4 => UNS
* INC # E9: 8,9 => UNS
* DIS # D4: 1,8 => CTR => D4: 4,6,7
* INC # D4: 4,6,7 => UNS
* DIS # F4: 1,8 => CTR => F4: 6
* PRF # F4: 6 => SOL
* DIS # D6: 1,8 => CTR => D6: 4,7,9
* INC # D6: 4,7,9 => UNS
* INC # C6: 1,8 => UNS
* DIS # C6: 4 => CTR => C6: 1,8
* INC # I4: 1,6 => UNS
* PRF # I4: 7 => SOL
* INC # D5: 1,6 => UNS
* DIS # D5: 2,4 => CTR => D5: 1,6
* INC # G1: 1,6 => UNS
* DIS # G1: 8 => CTR => G1: 1,6
* INC # D7: 1,2 => UNS
* INC # D8: 1,2 => UNS
* INC # D9: 1,2 => UNS
* INC # B8: 1,2 => UNS
* INC # C8: 1,2 => UNS
* INC # H8: 1,2 => UNS
* INC # D8: 5,9 => UNS
* INC # D8: 1,2,4 => UNS
* CNT  57 HDP CHAINS /  57 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* PRF # B2: 2,8 => SOL
* STA B2: 2,8
* CNT   1 HDP CHAINS /   1 HYP OPENED