Analysis of zz-www.sudokuoftheday.co.uk-20190103-absurd-base.sdk

Contents

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

level: medium

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

position: .8.6.4........92.3.7..2..5.6...........2..87...1..7..9...1.23......3...84...9.... initial

Autosolve

position: 283654...5..719283179.2..5.6.798....39.2..87.8.1..7..99.81723..71.43...843..9.... autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* PRF # G6: 5 => SOL
* DIS # I5: 4,6 => CTR => I5: 1,5
* PRF # I5: 1,5 => SOL
* DIS # I7: 4,6 => CTR => I7: 5
* PRF # I7: 5 => SOL
* DIS # B6: 4,5 => CTR => B6: 2
* DIS # I5: 4,6 => CTR => I5: 1,5
* PRF # I5: 1,5 => SOL
* PRF # I5: 1,5 => SOL
* DIS # I5: 4,6 => CTR => I5: 1,5
* PRF # F4: 1 => SOL
* PRF # H6: 4,6 => SOL
* DIS # I7: 4 => CTR => I7: 5,6
* DIS # I7: 4,6 => CTR => I7: 5
* PRF # I7: 5 => SOL
* PRF # H6: 4,6 => SOL
* CNT  16 HDP CHAINS /  42 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 # G6: 5 => SOL
* STA G6: 5
* CNT   1 HDP CHAINS /   8 HYP OPENED

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

Details

Positions

.8.6.4........92.3.7..2..5.6...........2..87...1..7..9...1.23......3...84...9.... initial
283654...5..719283179.2..5.6.798....39.2..87.8.1..7..99.81723..71.43...843..9.... autosolve
283654197546719283179823654657981432394265871821347569968172345715436928432598716 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (17)
B2: 4,6
C2: 4,6
D3: 3,8
F3: 3,8
H1: 1,9
I1: 1,7
G3: 4,6
I3: 4,6
C5: 4,5
E5: 4,6
F5: 1,5
D6: 3,5
E6: 4,6
B7: 5,6
F8: 5,6
D9: 5,8
H7: 4,6

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
F4,F5: 1.. / F4 = 1  =>  0 pairs (*) / F5 = 1  =>  0 pairs (X)
F5,I5: 1.. / F5 = 1  => 18 pairs (_) / I5 = 1  =>  0 pairs (*)
B4,B6: 2.. / B4 = 2  =>  0 pairs (X) / B6 = 2  => 18 pairs (_)
C8,C9: 2.. / C8 = 2  => 21 pairs (_) / C9 = 2  => 20 pairs (_)
B6,H6: 2.. / B6 = 2  => 18 pairs (_) / H6 = 2  =>  0 pairs (X)
C8,H8: 2.. / C8 = 2  => 21 pairs (_) / H8 = 2  => 20 pairs (_)
I4,I9: 2.. / I4 = 2  => 18 pairs (_) / I9 = 2  =>  0 pairs (X)
D3,F3: 3.. / D3 = 3  => 19 pairs (_) / F3 = 3  => 17 pairs (_)
F4,D6: 3.. / F4 = 3  => 19 pairs (_) / D6 = 3  => 17 pairs (_)
H4,H6: 3.. / H4 = 3  => 17 pairs (_) / H6 = 3  => 19 pairs (_)
F4,H4: 3.. / F4 = 3  => 19 pairs (_) / H4 = 3  => 17 pairs (_)
D6,H6: 3.. / D6 = 3  => 17 pairs (_) / H6 = 3  => 19 pairs (_)
D3,D6: 3.. / D3 = 3  => 19 pairs (_) / D6 = 3  => 17 pairs (_)
F3,F4: 3.. / F3 = 3  => 17 pairs (_) / F4 = 3  => 19 pairs (_)
B2,C2: 4.. / B2 = 4  =>  0 pairs (*) / C2 = 4  =>  0 pairs (X)
G3,I3: 4.. / G3 = 4  => 17 pairs (_) / I3 = 4  => 17 pairs (_)
E5,E6: 4.. / E5 = 4  =>  0 pairs (X) / E6 = 4  => 17 pairs (_)
H7,I7: 4.. / H7 = 4  => 17 pairs (_) / I7 = 4  =>  0 pairs (X)
C2,C5: 4.. / C2 = 4  =>  0 pairs (X) / C5 = 4  =>  0 pairs (_)
B7,I7: 5.. / B7 = 5  =>  0 pairs (X) / I7 = 5  =>  0 pairs (_)
D6,D9: 5.. / D6 = 5  => 19 pairs (_) / D9 = 5  => 17 pairs (_)
B2,C2: 6.. / B2 = 6  =>  0 pairs (X) / C2 = 6  =>  0 pairs (_)
G3,I3: 6.. / G3 = 6  => 17 pairs (_) / I3 = 6  => 17 pairs (_)
E5,E6: 6.. / E5 = 6  => 17 pairs (_) / E6 = 6  =>  0 pairs (X)
F8,F9: 6.. / F8 = 6  => 21 pairs (_) / F9 = 6  => 20 pairs (_)
E5,I5: 6.. / E5 = 6  => 17 pairs (_) / I5 = 6  =>  0 pairs (X)
B2,B7: 6.. / B2 = 6  =>  0 pairs (X) / B7 = 6  =>  0 pairs (_)
G1,I1: 7.. / G1 = 7  => 17 pairs (_) / I1 = 7  => 17 pairs (_)
G9,I9: 7.. / G9 = 7  => 17 pairs (_) / I9 = 7  => 17 pairs (_)
G1,G9: 7.. / G1 = 7  => 17 pairs (_) / G9 = 7  => 17 pairs (_)
I1,I9: 7.. / I1 = 7  => 17 pairs (_) / I9 = 7  => 17 pairs (_)
D3,F3: 8.. / D3 = 8  => 17 pairs (_) / F3 = 8  => 19 pairs (_)
D9,F9: 8.. / D9 = 8  => 19 pairs (_) / F9 = 8  => 17 pairs (_)
D3,D9: 8.. / D3 = 8  => 17 pairs (_) / D9 = 8  => 19 pairs (_)
F3,F9: 8.. / F3 = 8  => 19 pairs (_) / F9 = 8  => 17 pairs (_)
G1,H1: 9.. / G1 = 9  => 19 pairs (_) / H1 = 9  => 18 pairs (_)
G8,H8: 9.. / G8 = 9  => 18 pairs (_) / H8 = 9  => 19 pairs (_)
G1,G8: 9.. / G1 = 9  => 19 pairs (_) / G8 = 9  => 18 pairs (_)
H1,H8: 9.. / H1 = 9  => 18 pairs (_) / H8 = 9  => 19 pairs (_)
* DURATION: 0:00:46.560382  START: 02:40:34.237459  END: 02:41:20.797841 2019-05-01
* CP COUNT: (39)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (B2,B7,C2,C5,D3,D6,D9,E5,E6,F3,F5,F8,G3,H1,H7,I1,I3)
* 283654...5..719283179.2..5.6.798....39.2..87.8.1..7..99.81723..71.43...843..9....
* PAIR H1: 1,9 BLK 3
G1: 1,9,7                                # reduction candidate for 1,9
G1: 7                                    # 17 pairs
G1: 1,9                                  # 17 pairs
* PAIR I1: 1,7 BLK 3
G1: 1,7,9                                # reduction candidate for 1,7
G1: 9                                    # 19 pairs
G1: 1,7                                  # 18 pairs
* PAIR I1: 1,7 COL I
I9: 1,7,2,5,6                            # reduction candidate for 1,7
I9: 1,7                                  # 19 pairs
I9: 2,5,6                                # 17 pairs
* PAIR G3: 4,6 COL G
G6: 4,6,5                                # reduction candidate for 4,6
G6: 5 => SOLVED
* 283654197546719283179823654657981432394265871821347569968172345715436928432598716
G6: 4,6                                  # 23 pairs
* PAIR I3: 4,6 COL I
I5: 4,6,1,5                              # reduction candidate for 4,6
I5: 4,6 => CTR
* 283654...564719283179.2..5.6.798....3952.187.8.1..7..99581723..71.43...843..9....
I5: 1,5 => SOLVED
* 283654197546719283179823654657981432394265871821347569968172345715436928432598716
I7: 4,6,5                                # reduction candidate for 4,6
I7: 4,6 => CTR
* 283654...564719283179.2..5.6.798....3952.187.8.1..7..99581723..71.43...843..9....
I7: 5 => SOLVED
* 283654197546719283179823654657981432394265871821347569968172345715436928432598716
* PAIR C5: 4,5 BLK 4
B4: 4,5,2                                # reduction candidate for 4,5
B4: 4,5                                  # 18 pairs
B6: 4,5,2                                # reduction candidate for 4,5
B6: 4,5 => CTR
* 2836541975..719283179823.5.62798..3.3952.187.8413675299.817234.71243...843.598712
B6: 2                                    # 18 pairs
* PAIR C5: 4,5 ROW 5
I5: 4,5,1,6                              # reduction candidate for 4,5
I5: 4,5                                  # 19 pairs
I5: 1,6                                  # 18 pairs
* PAIR E5: 4,6 ROW 5
I5: 4,6,1,5                              # reduction candidate for 4,6
I5: 4,6 => CTR
* 283654...564719283179.2..5.6.798....3952.187.8.1..7..99581723..71.43...843..9....
I5: 1,5 => SOLVED
* 283654197546719283179823654657981432394265871821347569968172345715436928432598716
* PAIR F5: 1,5 BLK 5
F4: 1,5,3                                # reduction candidate for 1,5
F4: 3                                    # 19 pairs
F4: 1,5                                  # 17 pairs
* PAIR F5: 1,5 ROW 5
I5: 1,5,4,6                              # reduction candidate for 1,5
I5: 1,5 => SOLVED
* 283654197546719283179823654657981432394265871821347569968172345715436928432598716
I5: 4,6 => CTR
* 283654...564719283179.2..5.6.798....3952.187.8.1..7..99581723..71.43...843..9....
* PAIR D6: 3,5 BLK 5
F4: 3,5,1                                # reduction candidate for 3,5
F4: 1 => SOLVED
* 283654197546719283179823654657981432394265871821347569968172345715436928432598716
F4: 3,5                                  # 18 pairs
* PAIR E6: 4,6 ROW 6
G6: 4,6,5                                # reduction candidate for 4,6
G6: 4,6                                  # 23 pairs
H6: 4,6,2,3                              # reduction candidate for 4,6
H6: 4,6 => SOLVED
* 283654197546719283179823654657981432394265871821347569968172345715436928432598716
H6: 2,3                                  # 20 pairs
* PAIR B7: 5,6 BLK 7
C8: 5,6,2                                # reduction candidate for 5,6
C8: 5,6                                  # 20 pairs
C9: 5,6,2                                # reduction candidate for 5,6
C9: 5,6                                  # 21 pairs
* PAIR B7: 5,6 ROW 7
I7: 5,6,4                                # reduction candidate for 5,6
I7: 4 => CTR
* 283654...564719283179.2.4566.798....3952..87.8.1..7..995817236471.43...843..9....
I7: 5,6                                  # 17 pairs
* PAIR F8: 5,6 BLK 8
F9: 5,6,8                                # reduction candidate for 5,6
F9: 5,6                                  # 19 pairs
F9: 8                                    # 17 pairs
* PAIR F8: 5,6 ROW 8
C8: 5,6,2                                # reduction candidate for 5,6
C8: 5,6                                  # 20 pairs
G8: 5,6,9                                # reduction candidate for 5,6
G8: 5,6                                  # 19 pairs
* PAIR D9: 5,8 BLK 8
F9: 5,8,6                                # reduction candidate for 5,8
F9: 5,8                                  # 21 pairs
F9: 6                                    # 20 pairs
* PAIR H7: 4,6 BLK 9
I7: 4,6,5                                # reduction candidate for 4,6
I7: 4,6 => CTR
* 283654...564719283179.2..5.6.798....3952.187.8.1..7..99581723..71.43...843..9....
I7: 5 => SOLVED
* 283654197546719283179823654657981432394265871821347569968172345715436928432598716
* PAIR H7: 4,6 COL H
H6: 4,6,2,3                              # reduction candidate for 4,6
H6: 4,6 => SOLVED
* 283654197546719283179823654657981432394265871821347569968172345715436928432598716
H6: 2,3                                  # 20 pairs
* INCONCLUSIVE
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20190103-absurd-base-pr-000.dot
* REASONING
* PRF # G6: 5 => SOL
* DIS # I5: 4,6 => CTR => I5: 1,5
* PRF # I5: 1,5 => SOL
* DIS # I7: 4,6 => CTR => I7: 5
* PRF # I7: 5 => SOL
* DIS # B6: 4,5 => CTR => B6: 2
* DIS # I5: 4,6 => CTR => I5: 1,5
* PRF # I5: 1,5 => SOL
* PRF # I5: 1,5 => SOL
* DIS # I5: 4,6 => CTR => I5: 1,5
* PRF # F4: 1 => SOL
* PRF # H6: 4,6 => SOL
* DIS # I7: 4 => CTR => I7: 5,6
* DIS # I7: 4,6 => CTR => I7: 5
* PRF # I7: 5 => SOL
* PRF # H6: 4,6 => SOL
* CNT  16 HDP CHAINS /  42 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (B2,B7,C2,C5,D3,D6,D9,E5,E6,F3,F5,F8,G3,H1,H7,I1,I3)
* 283654...5..719283179.2..5.6.798....39.2..87.8.1..7..99.81723..71.43...843..9....
* PAIR H1: 1,9 BLK 3
G1: 1,9,7                                # reduction candidate for 1,9
G1: 7                                    # 17 pairs
G1: 1,9                                  # 17 pairs
* PAIR I1: 1,7 BLK 3
G1: 1,7,9                                # reduction candidate for 1,7
G1: 9                                    # 19 pairs
G1: 1,7                                  # 18 pairs
* PAIR I1: 1,7 COL I
I9: 1,7,2,5,6                            # reduction candidate for 1,7
I9: 1,7                                  # 19 pairs
I9: 2,5,6                                # 17 pairs
* PAIR G3: 4,6 COL G
G6: 4,6,5                                # reduction candidate for 4,6
G6: 5 => SOLVED
* 283654197546719283179823654657981432394265871821347569968172345715436928432598716
* DURATION: 0:00:06.005589  START: 02:41:50.150574  END: 02:41:56.156163 2019-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-www.sudokuoftheday.co.uk-20190103-absurd-base-pr-001.dot
* REASONING
* PRF # G6: 5 => SOL
* STA G6: 5
* CNT   1 HDP CHAINS /   8 HYP OPENED

Header Info

http://www.sudokuoftheday.co.uk/cgi-bin/sudoku1280.cgi?ACTION=archive2&USER=&MONTH=Jan&YEAR=2019, 20190103, absurd

Solution

position: 283654197546719283179823654657981432394265871821347569968172345715436928432598716 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 # G1: 1,9 => UNS
* INC # G1: 7 => UNS
* INC # G1: 1,7 => UNS
* INC # G1: 9 => UNS
* INC # I9: 1,7 => UNS
* INC # I9: 2,5,6 => UNS
* INC # G6: 4,6 => UNS
* PRF # G6: 5 => SOL
* DIS # I5: 4,6 => CTR => I5: 1,5
* PRF # I5: 1,5 => SOL
* DIS # I7: 4,6 => CTR => I7: 5
* PRF # I7: 5 => SOL
* INC # B4: 4,5 => UNS
* DIS # B6: 4,5 => CTR => B6: 2
* INC # B6: 2 => UNS
* INC # I5: 4,5 => UNS
* INC # I5: 1,6 => UNS
* DIS # I5: 4,6 => CTR => I5: 1,5
* PRF # I5: 1,5 => SOL
* INC # F4: 1,5 => UNS
* INC # F4: 3 => UNS
* PRF # I5: 1,5 => SOL
* DIS # I5: 4,6 => CTR => I5: 1,5
* INC # F4: 3,5 => UNS
* PRF # F4: 1 => SOL
* INC # G6: 4,6 => UNS
* PRF # H6: 4,6 => SOL
* INC # H6: 2,3 => UNS
* INC # C8: 5,6 => UNS
* INC # C9: 5,6 => UNS
* INC # I7: 5,6 => UNS
* DIS # I7: 4 => CTR => I7: 5,6
* INC # F9: 5,6 => UNS
* INC # F9: 8 => UNS
* INC # C8: 5,6 => UNS
* INC # G8: 5,6 => UNS
* INC # F9: 5,8 => UNS
* INC # F9: 6 => UNS
* DIS # I7: 4,6 => CTR => I7: 5
* PRF # I7: 5 => SOL
* PRF # H6: 4,6 => SOL
* INC # H6: 2,3 => UNS
* CNT  42 HDP CHAINS /  42 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # G1: 1,9 => UNS
* INC # G1: 7 => UNS
* INC # G1: 1,7 => UNS
* INC # G1: 9 => UNS
* INC # I9: 1,7 => UNS
* INC # I9: 2,5,6 => UNS
* INC # G6: 4,6 => UNS
* PRF # G6: 5 => SOL
* STA G6: 5
* CNT   8 HDP CHAINS /   8 HYP OPENED