Analysis of zz-www.sudokuoftheday.co.uk-20060709-absurd-base.sdk

Contents

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

level: medium

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

position: ..2...........26194.9..65..9.3.8......19.4.2....5..1.......3..6......28..7....4.. initial

Autosolve

position: ..2..9.4...7..26194.9..65.29.328176.7.19.4.2..2.5.719.....239.639...528.27..984.. autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # B3: 1 => CTR => B3: 3,8
* DIS # D2: 4 => CTR => D2: 3,8
* DIS # E1: 1,7 => CTR => E1: 5
* PRF # D3: 1,7 => SOL
* DIS # E8: 4 => CTR => E8: 1,7
* DIS # I1: 3,8 => CTR => I1: 7
* PRF # I1: 7 => SOL
* DIS # I1: 8 => CTR => I1: 3,7
* PRF # D3: 3,7 => SOL
* DIS # B5: 6,8 => CTR => B5: 5
* DIS # I6: 3 => CTR => I6: 4,8
* DIS # C7: 4,8 => CTR => C7: 5
* PRF # C7: 5 => SOL
* DIS # I6: 3,8 => CTR => I6: 4
* DIS # B7: 4 => CTR => B7: 1,8
* DIS # D8: 1,7 => CTR => D8: 4,6
* DIS # D8: 4,7 => CTR => D8: 1,6
* DIS # D8: 4,7 => CTR => D8: 1,6
* DIS # D8: 1,7 => CTR => D8: 4,6
* CNT  19 HDP CHAINS /  38 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: 1 => CTR => B3: 3,8
* PRF B3: 3,8 # D3: 1,7 => SOL
* STA B3: 3,8 + D3: 1,7
* CNT   2 HDP CHAINS /   3 HYP OPENED

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

Details

Positions

..2...........26194.9..65..9.3.8......19.4.2....5..1.......3..6......28..7....4.. initial
..2..9.4...7..26194.9..65.29.328176.7.19.4.2..2.5.719.....239.639...528.27..984.. autosolve
162359847537842619489716532943281765751964328628537194815423976394675281276198453 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (22)
A2: 5,8
B2: 3,8
E2: 4,5
E3: 1,7
G1: 3,8
H3: 3,7
B4: 4,5
A6: 6,8
C6: 4,8
E5: 3,6
E6: 3,6
I4: 4,5
G5: 3,8
A7: 1,8
C8: 4,6
C9: 5,6
D7: 4,7
D9: 1,6
H7: 5,7
I8: 1,7
H9: 3,5
I9: 1,3

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
A7,B7: 1.. / A7 = 1  => 23 pairs (_) / B7 = 1  => 20 pairs (_)
I8,I9: 1.. / I8 = 1  =>  0 pairs (*) / I9 = 1  =>  0 pairs (X)
D9,I9: 1.. / D9 = 1  =>  0 pairs (*) / I9 = 1  =>  0 pairs (X)
A1,A7: 1.. / A1 = 1  => 20 pairs (_) / A7 = 1  => 23 pairs (_)
E5,E6: 3.. / E5 = 3  =>  0 pairs (X) / E6 = 3  => 22 pairs (_)
H9,I9: 3.. / H9 = 3  =>  0 pairs (X) / I9 = 3  =>  0 pairs (_)
B2,D2: 3.. / B2 = 3  => 24 pairs (_) / D2 = 3  => 27 pairs (_)
E6,I6: 3.. / E6 = 3  => 22 pairs (_) / I6 = 3  =>  0 pairs (X)
G1,G5: 3.. / G1 = 3  =>  0 pairs (X) / G5 = 3  => 22 pairs (_)
H3,H9: 3.. / H3 = 3  =>  0 pairs (*) / H9 = 3  =>  0 pairs (X)
D2,E2: 4.. / D2 = 4  =>  0 pairs (X) / E2 = 4  => 27 pairs (_)
B4,C6: 4.. / B4 = 4  => 20 pairs (_) / C6 = 4  =>  0 pairs (X)
I4,I6: 4.. / I4 = 4  =>  0 pairs (X) / I6 = 4  => 20 pairs (_)
B4,I4: 4.. / B4 = 4  => 20 pairs (_) / I4 = 4  =>  0 pairs (X)
C6,I6: 4.. / C6 = 4  =>  0 pairs (X) / I6 = 4  => 20 pairs (_)
B4,B7: 4.. / B4 = 4  => 20 pairs (_) / B7 = 4  =>  0 pairs (X)
E2,E8: 4.. / E2 = 4  => 27 pairs (_) / E8 = 4  =>  0 pairs (X)
A1,A2: 5.. / A1 = 5  =>  0 pairs (X) / A2 = 5  => 27 pairs (_)
E1,E2: 5.. / E1 = 5  => 27 pairs (_) / E2 = 5  =>  0 pairs (X)
B4,B5: 5.. / B4 = 5  =>  0 pairs (X) / B5 = 5  => 20 pairs (_)
I4,I5: 5.. / I4 = 5  => 20 pairs (_) / I5 = 5  =>  0 pairs (X)
C7,C9: 5.. / C7 = 5  =>  0 pairs (*) / C9 = 5  =>  0 pairs (X)
H7,H9: 5.. / H7 = 5  =>  0 pairs (X) / H9 = 5  =>  0 pairs (_)
A1,E1: 5.. / A1 = 5  =>  0 pairs (X) / E1 = 5  => 27 pairs (_)
A2,E2: 5.. / A2 = 5  => 27 pairs (_) / E2 = 5  =>  0 pairs (X)
B4,I4: 5.. / B4 = 5  =>  0 pairs (X) / I4 = 5  => 20 pairs (_)
B5,I5: 5.. / B5 = 5  => 20 pairs (_) / I5 = 5  =>  0 pairs (X)
C7,H7: 5.. / C7 = 5  =>  0 pairs (*) / H7 = 5  =>  0 pairs (X)
C9,H9: 5.. / C9 = 5  =>  0 pairs (X) / H9 = 5  =>  0 pairs (_)
A1,B1: 6.. / A1 = 6  =>  0 pairs (X) / B1 = 6  => 22 pairs (_)
B5,A6: 6.. / B5 = 6  =>  0 pairs (X) / A6 = 6  => 22 pairs (_)
E5,E6: 6.. / E5 = 6  => 22 pairs (_) / E6 = 6  =>  0 pairs (X)
C8,C9: 6.. / C8 = 6  =>  0 pairs (X) / C9 = 6  =>  0 pairs (_)
D8,D9: 6.. / D8 = 6  =>  0 pairs (*) / D9 = 6  =>  0 pairs (X)
B5,E5: 6.. / B5 = 6  =>  0 pairs (X) / E5 = 6  => 22 pairs (_)
A6,E6: 6.. / A6 = 6  => 22 pairs (_) / E6 = 6  =>  0 pairs (X)
C8,D8: 6.. / C8 = 6  =>  0 pairs (X) / D8 = 6  =>  0 pairs (_)
C9,D9: 6.. / C9 = 6  =>  0 pairs (*) / D9 = 6  =>  0 pairs (X)
A1,A6: 6.. / A1 = 6  =>  0 pairs (X) / A6 = 6  => 22 pairs (_)
B1,B5: 6.. / B1 = 6  => 22 pairs (_) / B5 = 6  =>  0 pairs (X)
I1,H3: 7.. / I1 = 7  =>  0 pairs (*) / H3 = 7  =>  0 pairs (X)
H7,I8: 7.. / H7 = 7  =>  0 pairs (*) / I8 = 7  =>  0 pairs (X)
D7,H7: 7.. / D7 = 7  =>  0 pairs (X) / H7 = 7  =>  0 pairs (_)
H3,H7: 7.. / H3 = 7  =>  0 pairs (X) / H7 = 7  =>  0 pairs (_)
I1,I8: 7.. / I1 = 7  =>  0 pairs (*) / I8 = 7  =>  0 pairs (X)
D2,D3: 8.. / D2 = 8  => 27 pairs (_) / D3 = 8  => 24 pairs (_)
G1,I1: 8.. / G1 = 8  => 22 pairs (_) / I1 = 8  =>  0 pairs (X)
B3,D3: 8.. / B3 = 8  => 27 pairs (_) / D3 = 8  => 24 pairs (_)
C6,C7: 8.. / C6 = 8  => 20 pairs (_) / C7 = 8  =>  0 pairs (X)
G1,G5: 8.. / G1 = 8  => 22 pairs (_) / G5 = 8  =>  0 pairs (X)
* DURATION: 0:01:13.007682  START: 00:33:14.058813  END: 00:34:27.066495 2019-05-01
* CP COUNT: (50)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A2,A6,A7,B2,B4,C6,C8,C9,D7,D9,E2,E3,E5,E6,G1,G5,H3,H7,H9,I4,I8,I9)
* ..2..9.4...7..26194.9..65.29.328176.7.19.4.2..2.5.719.....239.639...528.27..984..
* PAIR B2: 3,8 BLK 1
B3: 3,8,1                                # reduction candidate for 3,8
B3: 1 => CTR
* ..2..9.4...7..26194198765329.328176.7.19.432..2.53719.1...2397639.7.528127..984..
B3: 3,8                                  # 30 pairs
* PAIR B2: 3,8 ROW 2
D2: 3,8,4                                # reduction candidate for 3,8
D2: 4 => CTR
* ..2..9.4..374526194.98.65329.328176.7.19.432..2.53719....72395639...528.27..984..
D2: 3,8                                  # 27 pairs
* PAIR E3: 1,7 BLK 2
D1: 1,7,3                                # reduction candidate for 1,7
D1: 1,7                                  # 29 pairs
E1: 1,7,5                                # reduction candidate for 1,7
E1: 1,7 => CTR
* 562..9.4.8374526194198765329.328176.7.196432.62.53719.1..72395639...528.27..984..
E1: 5                                    # 27 pairs
D3: 1,7,3,8                              # reduction candidate for 1,7
D3: 1,7 => SOLVED
* 162359847537842619489716532943281765751964328628537194815423976394675281276198453
D3: 3,8                                  # 23 pairs
* PAIR E3: 1,7 COL E
E8: 1,7,4                                # reduction candidate for 1,7
E8: 4 => CTR
* 5623.9.4...74526194.98.65.29.328176.7.19.4.2..2.5.719....723956396145287275698431
E8: 1,7                                  # 27 pairs
* PAIR G1: 3,8 BLK 3
I1: 3,8,7                                # reduction candidate for 3,8
I1: 3,8 => CTR
* 5.2.79.4...7.526194.9.165729.328176.7.19.4.2..2.5.719....723956396145287275698431
I1: 7 => SOLVED
* 162359847537842619489716532943281765751964328628537194815423976394675281276198453
* PAIR H3: 3,7 BLK 3
I1: 3,7,8                                # reduction candidate for 3,7
I1: 8 => CTR
* ..2.79348..7.526194.9.165729.328176.7.19.482..2.5.719....72395639...5287275698431
I1: 3,7                                  # 22 pairs
* PAIR H3: 3,7 ROW 3
D3: 3,7,1,8                              # reduction candidate for 3,7
D3: 3,7 => SOLVED
* 162359847537842619489716532943281765751964328628537194815423976394675281276198453
D3: 1,8                                  # 23 pairs
* PAIR A6: 6,8 BLK 4
B5: 6,8,5                                # reduction candidate for 6,8
B5: 6,8 => CTR
* 5.2.79.4...7.526194.9.165729532817647.19.4.25.245.719.148723956396145287275698431
B5: 5                                    # 20 pairs
* PAIR C6: 4,8 ROW 6
I6: 4,8,3                                # reduction candidate for 4,8
I6: 3 => CTR
* ..2.79348..7.526194.9.165.29.32817647.19.4.25.245.7193.48723956396..5287275698431
I6: 4,8                                  # 22 pairs
* PAIR C6: 4,8 COL C
C7: 4,8,5                                # reduction candidate for 4,8
C7: 4,8 => CTR
* 5.2.79.4...7.526194.9.165729.328176.7.19.4.2..2.5.719....723956396145287275698431
C7: 5 => SOLVED
* 162359847537842619489716532943281765751964328628537194815423976394675281276198453
* PAIR G5: 3,8 BLK 6
I5: 3,8,5                                # reduction candidate for 3,8
I5: 3,8                                  # 20 pairs
I6: 3,8,4                                # reduction candidate for 3,8
I6: 3,8 => CTR
* 5.2.79.4...7.526194.9.165729532817647.19.4.25.245.719.148723956396145287275698431
I6: 4                                    # 20 pairs
* PAIR A7: 1,8 BLK 7
B7: 1,8,4                                # reduction candidate for 1,8
B7: 4 => CTR
* 5.2.79.4...7.526194.9.165729532817647.19.4.25.245.719.148723956396145287275698431
B7: 1,8                                  # 20 pairs
* PAIR C8: 4,6 ROW 8
D8: 4,6,1,7                              # reduction candidate for 4,6
D8: 1,7 => CTR
* 5623.9.4...74526194.98.65729.328176.7.19.4.2..2.5.719....723956396145287275698431
D8: 4,6                                  # 27 pairs
* PAIR D7: 4,7 BLK 8
D8: 4,7,1,6                              # reduction candidate for 4,7
D8: 4,7 => CTR
* ..2..9.4...7..26194.9..65729.328176.7.19.4.2..2.5.719....72395639641528.275698431
D8: 1,6                                  # 27 pairs
E8: 4,7,1                                # reduction candidate for 4,7
E8: 4,7                                  # 27 pairs
* PAIR D9: 1,6 BLK 8
D8: 1,6,4,7                              # reduction candidate for 1,6
D8: 4,7 => CTR
* ..2..9.4...7..26194.9..65729.328176.7.19.4.2..2.5.719....72395639641528.275698431
D8: 1,6                                  # 27 pairs
* PAIR I8: 1,7 ROW 8
D8: 1,7,4,6                              # reduction candidate for 1,7
D8: 1,7 => CTR
* 5623.9.4...74526194.98.65729.328176.7.19.4.2..2.5.719....723956396145287275698431
D8: 4,6                                  # 27 pairs
E8: 1,7,4                                # reduction candidate for 1,7
E8: 1,7                                  # 27 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060709-absurd-base-pr-000.dot
* REASONING
* DIS # B3: 1 => CTR => B3: 3,8
* DIS # D2: 4 => CTR => D2: 3,8
* DIS # E1: 1,7 => CTR => E1: 5
* PRF # D3: 1,7 => SOL
* DIS # E8: 4 => CTR => E8: 1,7
* DIS # I1: 3,8 => CTR => I1: 7
* PRF # I1: 7 => SOL
* DIS # I1: 8 => CTR => I1: 3,7
* PRF # D3: 3,7 => SOL
* DIS # B5: 6,8 => CTR => B5: 5
* DIS # I6: 3 => CTR => I6: 4,8
* DIS # C7: 4,8 => CTR => C7: 5
* PRF # C7: 5 => SOL
* DIS # I6: 3,8 => CTR => I6: 4
* DIS # B7: 4 => CTR => B7: 1,8
* DIS # D8: 1,7 => CTR => D8: 4,6
* DIS # D8: 4,7 => CTR => D8: 1,6
* DIS # D8: 4,7 => CTR => D8: 1,6
* DIS # D8: 1,7 => CTR => D8: 4,6
* CNT  19 HDP CHAINS /  38 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A2,A6,A7,B2,B4,C6,C8,C9,D7,D9,E2,E3,E5,E6,G1,G5,H3,H7,H9,I4,I8,I9)
* ..2..9.4...7..26194.9..65.29.328176.7.19.4.2..2.5.719.....239.639...528.27..984..
* PAIR B2: 3,8 BLK 1
B3: 3,8,1                                # reduction candidate for 3,8
B3: 1 => CTR
* ..2..9.4...7..26194198765329.328176.7.19.432..2.53719.1...2397639.7.528127..984..
* PAIR E3: 1,7 BLK 2
D3: 1,7,3,8                              # reduction candidate for 1,7
D3: 1,7 => SOLVED
* 162359847537842619489716532943281765751964328628537194815423976394675281276198453
* DURATION: 0:00:03.594331  START: 00:34:58.612593  END: 00:35:02.206924 2019-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20060709-absurd-base-pr-001.dot
* REASONING
* DIS # B3: 1 => CTR => B3: 3,8
* PRF B3: 3,8 # D3: 1,7 => SOL
* STA B3: 3,8 + D3: 1,7
* CNT   2 HDP CHAINS /   3 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Jul&YEAR=2006, 20060709, absurd

Solution

position: 162359847537842619489716532943281765751964328628537194815423976394675281276198453 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 # B3: 3,8 => UNS
* DIS # B3: 1 => CTR => B3: 3,8
* INC # D2: 3,8 => UNS
* DIS # D2: 4 => CTR => D2: 3,8
* INC # D1: 1,7 => UNS
* DIS # E1: 1,7 => CTR => E1: 5
* INC # E1: 5 => UNS
* PRF # D3: 1,7 => SOL
* INC # D3: 3,8 => UNS
* INC # E8: 1,7 => UNS
* DIS # E8: 4 => CTR => E8: 1,7
* DIS # I1: 3,8 => CTR => I1: 7
* PRF # I1: 7 => SOL
* INC # I1: 3,7 => UNS
* DIS # I1: 8 => CTR => I1: 3,7
* PRF # D3: 3,7 => SOL
* INC # D3: 1,8 => UNS
* DIS # B5: 6,8 => CTR => B5: 5
* INC # B5: 5 => UNS
* INC # I6: 4,8 => UNS
* DIS # I6: 3 => CTR => I6: 4,8
* DIS # C7: 4,8 => CTR => C7: 5
* PRF # C7: 5 => SOL
* INC # I5: 3,8 => UNS
* DIS # I6: 3,8 => CTR => I6: 4
* INC # I6: 4 => UNS
* INC # B7: 1,8 => UNS
* DIS # B7: 4 => CTR => B7: 1,8
* INC # D8: 4,6 => UNS
* DIS # D8: 1,7 => CTR => D8: 4,6
* DIS # D8: 4,7 => CTR => D8: 1,6
* INC # D8: 1,6 => UNS
* INC # E8: 4,7 => UNS
* INC # D8: 1,6 => UNS
* DIS # D8: 4,7 => CTR => D8: 1,6
* DIS # D8: 1,7 => CTR => D8: 4,6
* INC # D8: 4,6 => UNS
* INC # E8: 1,7 => UNS
* CNT  38 HDP CHAINS /  38 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # B3: 3,8 => UNS
* DIS # B3: 1 => CTR => B3: 3,8
* PRF B3: 3,8 # D3: 1,7 => SOL
* STA B3: 3,8 + D3: 1,7
* CNT   3 HDP CHAINS /   3 HYP OPENED