Analysis of zz-www.sudokuoftheday.co.uk-20190305-absurd-base.sdk

Contents

Sudoku from http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Mar&YEAR=2019

level: medium

Sudoku from http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Mar&YEAR=2019

position: ....9..34....6..598...3.....9..761...625.3.9.4.7.......1....4..........3..3..9.2. initial

Autosolve

position: ....9..34.3..6..598.9.3.6..39..7614.1625437984.79..36.91.3..4........9.3..3..952. autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* PRF # A1: 2,7 => SOL
* DIS # A8: 2,7 => CTR => A8: 5,6
* DIS # D2: 2,4 => CTR => D2: 1,7,8
* DIS # F3: 2,4 => CTR => F3: 5
* DIS # B3: 5 => CTR => B3: 2,4
* DIS # D1: 2,8 => CTR => D1: 1,7
* DIS # D2: 2,8 => CTR => D2: 1,4,7
* DIS # F2: 2,8 => CTR => F2: 1,4,7
* DIS # I9: 6 => CTR => I9: 1,7
* DIS # C8: 5,8 => CTR => C8: 4,6
* DIS # B8: 5,8 => CTR => B8: 2,4,7
* DIS # F6: 2,8 => CTR => F6: 1
* DIS # D1: 2,8 => CTR => D1: 1,7
* DIS # D2: 2,8 => CTR => D2: 1,4,7
* DIS # A8: 6,7 => CTR => A8: 2,5
* DIS # D9: 6,7 => CTR => D9: 1,4,8
* PRF # A1: 6,7 => SOL
* DIS # A1: 2,5 => CTR => A1: 6,7
* DIS # D8: 1,8 => CTR => D8: 4,6,7
* DIS # F8: 1,8 => CTR => F8: 4,7
* DIS # D9: 1,8 => CTR => D9: 4,6,7
* DIS # E6: 1,8 => CTR => E6: 2
* DIS # F7: 7,8 => CTR => F7: 2
* CNT  23 HDP CHAINS /  61 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 # A1: 2,7 => SOL
* STA A1: 2,7
* CNT   1 HDP CHAINS /   1 HYP OPENED

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

Details

Positions

....9..34....6..598...3.....9..761...625.3.9.4.7.......1....4..........3..3..9.2. initial
....9..34.3..6..598.9.3.6..39..7614.1625437984.79..36.91.3..4........9.3..3..952. autosolve
756198234231764859849235617395876142162543798487921365918352476524617983673489521 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (16)
A2: 2,7
C2: 1,4
D3: 2,4
G1: 2,8
G2: 2,8
H3: 1,7
I3: 1,7
C4: 5,8
B6: 5,8
D4: 2,8
I4: 2,5
I6: 2,5
A9: 6,7
E9: 1,8
H7: 7,8
I7: 6,7

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
C1,C2: 1.. / C1 = 1  =>  0 pairs (X) / C2 = 1  =>  0 pairs (_)
H3,I3: 1.. / H3 = 1  => 23 pairs (_) / I3 = 1  => 19 pairs (_)
E6,F6: 1.. / E6 = 1  =>  0 pairs (X) / F6 = 1  => 17 pairs (_)
H8,I9: 1.. / H8 = 1  => 19 pairs (_) / I9 = 1  => 23 pairs (_)
H3,H8: 1.. / H3 = 1  => 23 pairs (_) / H8 = 1  => 19 pairs (_)
I3,I9: 1.. / I3 = 1  => 19 pairs (_) / I9 = 1  => 23 pairs (_)
G1,G2: 2.. / G1 = 2  => 15 pairs (_) / G2 = 2  =>  0 pairs (X)
I4,I6: 2.. / I4 = 2  => 14 pairs (_) / I6 = 2  =>  0 pairs (X)
A8,B8: 2.. / A8 = 2  =>  0 pairs (X) / B8 = 2  => 18 pairs (_)
E7,F7: 2.. / E7 = 2  =>  0 pairs (X) / F7 = 2  => 14 pairs (_)
D4,I4: 2.. / D4 = 2  =>  0 pairs (X) / I4 = 2  => 14 pairs (_)
E6,E7: 2.. / E6 = 2  => 14 pairs (_) / E7 = 2  =>  0 pairs (X)
C2,B3: 4.. / C2 = 4  =>  0 pairs (X) / B3 = 4  =>  0 pairs (_)
B9,D9: 4.. / B9 = 4  =>  0 pairs (X) / D9 = 4  =>  0 pairs (_)
C2,C8: 4.. / C2 = 4  =>  0 pairs (X) / C8 = 4  =>  0 pairs (_)
F1,F3: 5.. / F1 = 5  =>  0 pairs (X) / F3 = 5  => 17 pairs (_)
C4,B6: 5.. / C4 = 5  => 14 pairs (_) / B6 = 5  =>  0 pairs (X)
I4,I6: 5.. / I4 = 5  =>  0 pairs (X) / I6 = 5  => 14 pairs (_)
E7,E8: 5.. / E7 = 5  => 14 pairs (_) / E8 = 5  =>  0 pairs (X)
B3,F3: 5.. / B3 = 5  =>  0 pairs (X) / F3 = 5  => 17 pairs (_)
C4,I4: 5.. / C4 = 5  => 14 pairs (_) / I4 = 5  =>  0 pairs (X)
B6,I6: 5.. / B6 = 5  =>  0 pairs (X) / I6 = 5  => 14 pairs (_)
C7,E7: 5.. / C7 = 5  =>  0 pairs (X) / E7 = 5  => 14 pairs (_)
A1,A8: 5.. / A1 = 5  =>  0 pairs (X) / A8 = 5  => 14 pairs (_)
A1,C1: 6.. / A1 = 6  =>  0 pairs (X) / C1 = 6  =>  0 pairs (_)
D8,D9: 6.. / D8 = 6  => 16 pairs (_) / D9 = 6  =>  0 pairs (X)
I7,I9: 6.. / I7 = 6  => 19 pairs (_) / I9 = 6  =>  0 pairs (X)
C7,I7: 6.. / C7 = 6  =>  0 pairs (X) / I7 = 6  => 19 pairs (_)
H3,I3: 7.. / H3 = 7  => 19 pairs (_) / I3 = 7  => 23 pairs (_)
G1,G2: 8.. / G1 = 8  =>  0 pairs (X) / G2 = 8  => 15 pairs (_)
C4,B6: 8.. / C4 = 8  =>  0 pairs (X) / B6 = 8  => 14 pairs (_)
H7,H8: 8.. / H7 = 8  => 19 pairs (_) / H8 = 8  => 14 pairs (_)
C4,D4: 8.. / C4 = 8  =>  0 pairs (X) / D4 = 8  => 14 pairs (_)
* DURATION: 0:00:59.741107  START: 04:14:59.514991  END: 04:15:59.256098 2019-05-01
* CP COUNT: (33)
* CLUE FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A2,A9,B6,C2,C4,D3,D4,E9,G1,G2,H3,H7,I3,I4,I6,I7)
* ....9..34.3..6..598.9.3.6..39..7614.1625437984.79..36.91.3..4........9.3..3..952.
* PAIR A2: 2,7 BLK 1
A1: 2,7,5,6                              # reduction candidate for 2,7
A1: 2,7 => SOLVED
* 756198234231764859849235617395876142162543798487921365918352476524617983673489521
A1: 5,6                                  # 17 pairs
B1: 2,7,5                                # reduction candidate for 2,7
B1: 2,7                                  # 19 pairs
* PAIR A2: 2,7 ROW 2
D2: 2,7,1,4,8                            # reduction candidate for 2,7
D2: 2,7                                  # 17 pairs
F2: 2,7,1,4,8                            # reduction candidate for 2,7
F2: 2,7                                  # 17 pairs
* PAIR A2: 2,7 COL A
A8: 2,7,5,6                              # reduction candidate for 2,7
A8: 2,7 => CTR
* 526197.34.31.6..598492356..39.8761421625437984879..36591.3..4.6.546..9.3673489521
A8: 5,6                                  # 20 pairs
* PAIR C2: 1,4 ROW 2
D2: 1,4,2,7,8                            # reduction candidate for 1,4
D2: 1,4                                  # 17 pairs
F2: 1,4,2,7,8                            # reduction candidate for 1,4
F2: 1,4                                  # 17 pairs
* PAIR D3: 2,4 BLK 2
D2: 2,4,1,7,8                            # reduction candidate for 2,4
D2: 2,4 => CTR
* ....9..34.342618598294356..39587614216254379848791236591.3..4.......49.3.43.8952.
D2: 1,7,8                                # 16 pairs
F2: 2,4,1,7,8                            # reduction candidate for 2,4
F2: 2,4                                  # 18 pairs
F3: 2,4,5                                # reduction candidate for 2,4
F3: 2,4 => CTR
* .7..9583423..6..59859.3.6..3958761421625437984879..36591.3524..52....9.3.43.8952.
F3: 5                                    # 17 pairs
* PAIR D3: 2,4 ROW 3
B3: 2,4,5                                # reduction candidate for 2,4
B3: 5 => CTR
* .71295834234.6..59859.3.6..3958761421625437984879..36591.3524..52....9.3.43.8952.
B3: 2,4                                  # 17 pairs
* PAIR G1: 2,8 ROW 1
D1: 2,8,1,7                              # reduction candidate for 2,8
D1: 2,8 => CTR
* 671.95.342341678598594326..39..7614.1625437984.79..36.91.3..4..52..149.3743689521
D1: 1,7                                  # 17 pairs
F1: 2,8,1,5,7                            # reduction candidate for 2,8
F1: 2,8                                  # 20 pairs
* PAIR G2: 2,8 ROW 2
D2: 2,8,1,4,7                            # reduction candidate for 2,8
D2: 2,8 => CTR
* ..6.9..34731.64.598.9.3.6..39..7614.1625437984.79..36.91.3..4........9.3..3..952.
D2: 1,4,7                                # 16 pairs
F2: 2,8,1,4,7                            # reduction candidate for 2,8
F2: 2,8 => CTR
* ..6.9..3473146..598492356..39.8761421625437984879..36591.3..4.6..46..9.36731.952.
F2: 1,4,7                                # 16 pairs
* PAIR H3: 1,7 COL H
H8: 1,7,8                                # reduction candidate for 1,7
H8: 1,7                                  # 19 pairs
H8: 8                                    # 14 pairs
* PAIR I3: 1,7 COL I
I9: 1,7,6                                # reduction candidate for 1,7
I9: 6 => CTR
* ....9..34.3..6..598.9.3.67139..7614.1625437984.79..36.916352487...68.913783419526
I9: 1,7                                  # 19 pairs
* PAIR C4: 5,8 COL C
C7: 5,8,6                                # reduction candidate for 5,8
C7: 5,8                                  # 19 pairs
C8: 5,8,4,6                              # reduction candidate for 5,8
C8: 5,8 => CTR
* 671.95.3423476185985923467139587614.1625437984.79..36.916352487...6..9137.3..9526
C8: 4,6                                  # 17 pairs
* PAIR B6: 5,8 COL B
B8: 5,8,2,4,7                            # reduction candidate for 5,8
B8: 5,8 => CTR
* 5.6.9..34731.6..598492356..39.8761421625437984879..36591.3..4.62546..9.36734.952.
B8: 2,4,7                                # 16 pairs
* PAIR D4: 2,8 BLK 5
E6: 2,8,1                                # reduction candidate for 2,8
E6: 2,8                                  # 17 pairs
F6: 2,8,1                                # reduction candidate for 2,8
F6: 2,8 => CTR
* 5.6.9..34.31.6..598492356..39.8761421625437984.791.36.91.32.4......5.9.3..3.8952.
F6: 1                                    # 17 pairs
* PAIR D4: 2,8 COL D
D1: 2,8,1,7                              # reduction candidate for 2,8
D1: 2,8 => CTR
* 671.95.342341678598594326..39..7614.1625437984.79..36.91.3..4..52..149.3743689521
D1: 1,7                                  # 17 pairs
D2: 2,8,1,4,7                            # reduction candidate for 2,8
D2: 2,8 => CTR
* ..6.9..34731.64.598.9.3.6..39..7614.1625437984.79..36.91.3..4........9.3..3..952.
D2: 1,4,7                                # 16 pairs
* PAIR A9: 6,7 BLK 7
A8: 6,7,2,5                              # reduction candidate for 6,7
A8: 6,7 => CTR
* 5.6.9..34231.6.8598492356..39.8761421625437984879..36591.3..4.6......9.3..3..952.
A8: 2,5                                  # 17 pairs
* PAIR A9: 6,7 ROW 9
D9: 6,7,1,4,8                            # reduction candidate for 6,7
D9: 6,7 => CTR
* 671.95.34234.6.859859.3.6173958761421625437984879..365918352476526.1.983743689521
D9: 1,4,8                                # 16 pairs
I9: 6,7,1                                # reduction candidate for 6,7
I9: 6,7                                  # 19 pairs
* PAIR A9: 6,7 COL A
A1: 6,7,2,5                              # reduction candidate for 6,7
A1: 6,7 => SOLVED
* 756198234231764859849235617395876142162543798487921365918352476524617983673489521
A1: 2,5 => CTR
* ..6.9..34731.6..598492356..39.8761421625437984879..36591.3..4.6..4...9.3.73489521
* PAIR E9: 1,8 BLK 8
D8: 1,8,4,6,7                            # reduction candidate for 1,8
D8: 1,8 => CTR
* .7..9..34234761859859432617395.7614.1625437984.79..36.91.3..4.6.....49.3743689521
D8: 4,6,7                                # 16 pairs
E8: 1,8,5                                # reduction candidate for 1,8
E8: 1,8                                  # 14 pairs
F8: 1,8,4,7                              # reduction candidate for 1,8
F8: 1,8 => CTR
* ....9..34.3..6..598.923.6..3958761421625437984879..36591.3524......1.9.3..3.8952.
F8: 4,7                                  # 17 pairs
D9: 1,8,4,6,7                            # reduction candidate for 1,8
D9: 1,8 => CTR
* ....9..34.34.6..598.943.6..39..7614.1625437984.79..36.91.3.7486...6.49.3643..9527
D9: 4,6,7                                # 16 pairs
* PAIR E9: 1,8 COL E
E6: 1,8,2                                # reduction candidate for 1,8
E6: 1,8 => CTR
* 5.6.9..34.31.6..598492356..39.8761421625437984.79..36.91.32.4......5.9.3..3..952.
E6: 2                                    # 14 pairs
* PAIR H7: 7,8 BLK 9
H8: 7,8,1                                # reduction candidate for 7,8
H8: 7,8                                  # 23 pairs
H8: 1                                    # 19 pairs
* PAIR H7: 7,8 ROW 7
F7: 7,8,2                                # reduction candidate for 7,8
F7: 7,8 => CTR
* 5.6.9..34.31.6..598492356..39.8761421625437984.79..36.91.32.4......5.9.3..3..952.
F7: 2                                    # 14 pairs
* PAIR I7: 6,7 BLK 9
I9: 6,7,1                                # reduction candidate for 6,7
I9: 1                                    # 23 pairs
I9: 6,7                                  # 19 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20190305-absurd-base-pr-000.dot
* REASONING
* PRF # A1: 2,7 => SOL
* DIS # A8: 2,7 => CTR => A8: 5,6
* DIS # D2: 2,4 => CTR => D2: 1,7,8
* DIS # F3: 2,4 => CTR => F3: 5
* DIS # B3: 5 => CTR => B3: 2,4
* DIS # D1: 2,8 => CTR => D1: 1,7
* DIS # D2: 2,8 => CTR => D2: 1,4,7
* DIS # F2: 2,8 => CTR => F2: 1,4,7
* DIS # I9: 6 => CTR => I9: 1,7
* DIS # C8: 5,8 => CTR => C8: 4,6
* DIS # B8: 5,8 => CTR => B8: 2,4,7
* DIS # F6: 2,8 => CTR => F6: 1
* DIS # D1: 2,8 => CTR => D1: 1,7
* DIS # D2: 2,8 => CTR => D2: 1,4,7
* DIS # A8: 6,7 => CTR => A8: 2,5
* DIS # D9: 6,7 => CTR => D9: 1,4,8
* PRF # A1: 6,7 => SOL
* DIS # A1: 2,5 => CTR => A1: 6,7
* DIS # D8: 1,8 => CTR => D8: 4,6,7
* DIS # F8: 1,8 => CTR => F8: 4,7
* DIS # D9: 1,8 => CTR => D9: 4,6,7
* DIS # E6: 1,8 => CTR => E6: 2
* DIS # F7: 7,8 => CTR => F7: 2
* CNT  23 HDP CHAINS /  61 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A2,A9,B6,C2,C4,D3,D4,E9,G1,G2,H3,H7,I3,I4,I6,I7)
* ....9..34.3..6..598.9.3.6..39..7614.1625437984.79..36.91.3..4........9.3..3..952.
* PAIR A2: 2,7 BLK 1
A1: 2,7,5,6                              # reduction candidate for 2,7
A1: 2,7 => SOLVED
* 756198234231764859849235617395876142162543798487921365918352476524617983673489521
* DURATION: 0:00:02.076354  START: 04:16:53.421210  END: 04:16:55.497564 2019-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20190305-absurd-base-pr-001.dot
* REASONING
* PRF # A1: 2,7 => SOL
* STA A1: 2,7
* CNT   1 HDP CHAINS /   1 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Mar&YEAR=2019, 20190305, absurd

Solution

position: 756198234231764859849235617395876142162543798487921365918352476524617983673489521 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 # A1: 2,7 => SOL
* INC # A1: 5,6 => UNS
* INC # B1: 2,7 => UNS
* INC # D2: 2,7 => UNS
* INC # F2: 2,7 => UNS
* DIS # A8: 2,7 => CTR => A8: 5,6
* INC # A8: 5,6 => UNS
* INC # D2: 1,4 => UNS
* INC # F2: 1,4 => UNS
* DIS # D2: 2,4 => CTR => D2: 1,7,8
* INC # D2: 1,7,8 => UNS
* INC # F2: 2,4 => UNS
* DIS # F3: 2,4 => CTR => F3: 5
* INC # F3: 5 => UNS
* INC # B3: 2,4 => UNS
* DIS # B3: 5 => CTR => B3: 2,4
* DIS # D1: 2,8 => CTR => D1: 1,7
* INC # D1: 1,7 => UNS
* INC # F1: 2,8 => UNS
* DIS # D2: 2,8 => CTR => D2: 1,4,7
* INC # D2: 1,4,7 => UNS
* DIS # F2: 2,8 => CTR => F2: 1,4,7
* INC # F2: 1,4,7 => UNS
* INC # H8: 1,7 => UNS
* INC # H8: 8 => UNS
* INC # I9: 1,7 => UNS
* DIS # I9: 6 => CTR => I9: 1,7
* INC # C7: 5,8 => UNS
* DIS # C8: 5,8 => CTR => C8: 4,6
* INC # C8: 4,6 => UNS
* DIS # B8: 5,8 => CTR => B8: 2,4,7
* INC # B8: 2,4,7 => UNS
* INC # E6: 2,8 => UNS
* DIS # F6: 2,8 => CTR => F6: 1
* INC # F6: 1 => UNS
* DIS # D1: 2,8 => CTR => D1: 1,7
* INC # D1: 1,7 => UNS
* DIS # D2: 2,8 => CTR => D2: 1,4,7
* INC # D2: 1,4,7 => UNS
* DIS # A8: 6,7 => CTR => A8: 2,5
* INC # A8: 2,5 => UNS
* DIS # D9: 6,7 => CTR => D9: 1,4,8
* INC # D9: 1,4,8 => UNS
* INC # I9: 6,7 => UNS
* PRF # A1: 6,7 => SOL
* DIS # A1: 2,5 => CTR => A1: 6,7
* DIS # D8: 1,8 => CTR => D8: 4,6,7
* INC # D8: 4,6,7 => UNS
* INC # E8: 1,8 => UNS
* DIS # F8: 1,8 => CTR => F8: 4,7
* INC # F8: 4,7 => UNS
* DIS # D9: 1,8 => CTR => D9: 4,6,7
* INC # D9: 4,6,7 => UNS
* DIS # E6: 1,8 => CTR => E6: 2
* INC # E6: 2 => UNS
* INC # H8: 7,8 => UNS
* INC # H8: 1 => UNS
* DIS # F7: 7,8 => CTR => F7: 2
* INC # F7: 2 => UNS
* INC # I9: 6,7 => UNS
* INC # I9: 1 => UNS
* CNT  61 HDP CHAINS /  61 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* PRF # A1: 2,7 => SOL
* STA A1: 2,7
* CNT   1 HDP CHAINS /   1 HYP OPENED