Analysis of xx-top500-285-base.sdk

Contents

Original Sudoku

level: medium

Original Sudoku

position: ...2.4.5..1............7...4......7.5...1.......6....9....8.6.13.7............2.. initial

Autosolve

position: 7..2.415..1....7.....1.79..4.1....7.57.41.3.....675419...78.6.13.79.1...1..54.2.7 autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # B9: 6,9 => CTR => B9: 8
* DIS # C9: 8 => CTR => C9: 6,9
* PRF # C6: 2,8 => SOL
* DIS # A3: 2,8 => CTR => A3: 6
* PRF # I4: 5,8 => SOL
* DIS # A2: 6 => CTR => A2: 2,9
* PRF # I8: 4 => SOL
* PRF # I8: 4,8 => SOL
* CNT   8 HDP CHAINS /  23 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 # B9: 6,9 => CTR => B9: 8
* PRF B9: 8 # C6: 2,8 => SOL
* STA B9: 8 + C6: 2,8
* CNT   2 HDP CHAINS /   4 HYP OPENED

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

Details

Positions

...2.4.5..1............7...4......7.5...1.......6....9....8.6.13.7............2.. initial
7..2.415..1....7.....1.79..4.1....7.57.41.3.....675419...78.6.13.79.1...1..54.2.7 autosolve
798234156215896743643157928461329875579418362832675419954782631327961584186543297 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (18)
B3: 4,5
D2: 3,8
B4: 6,9
C5: 6,9
A6: 2,8
D4: 3,8
G4: 5,8
A7: 2,9
B7: 4,5
C7: 4,5
B8: 2,6
F7: 2,3
E8: 2,6
F9: 3,6
H7: 3,9
G8: 5,8
H8: 4,8
H9: 3,9

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
A7,B8: 2.. / A7 = 2  =>  0 pairs (X) / B8 = 2  =>  0 pairs (_)
F7,E8: 2.. / F7 = 2  =>  0 pairs (*) / E8 = 2  =>  0 pairs (X)
A7,F7: 2.. / A7 = 2  =>  0 pairs (X) / F7 = 2  =>  0 pairs (_)
B8,E8: 2.. / B8 = 2  =>  0 pairs (*) / E8 = 2  =>  0 pairs (X)
B6,B8: 2.. / B6 = 2  =>  0 pairs (X) / B8 = 2  =>  0 pairs (_)
E4,E8: 2.. / E4 = 2  =>  0 pairs (*) / E8 = 2  =>  0 pairs (X)
B6,C6: 3.. / B6 = 3  =>  0 pairs (*) / C6 = 3  =>  0 pairs (X)
D4,E4: 3.. / D4 = 3  => 18 pairs (_) / E4 = 3  =>  0 pairs (X)
F7,F9: 3.. / F7 = 3  =>  0 pairs (X) / F9 = 3  =>  0 pairs (_)
H7,H9: 3.. / H7 = 3  =>  0 pairs (*) / H9 = 3  =>  0 pairs (X)
F7,H7: 3.. / F7 = 3  =>  0 pairs (X) / H7 = 3  =>  0 pairs (_)
F9,H9: 3.. / F9 = 3  =>  0 pairs (*) / H9 = 3  =>  0 pairs (X)
B1,B6: 3.. / B1 = 3  => 24 pairs (_) / B6 = 3  =>  0 pairs (*)
D2,D4: 3.. / D2 = 3  =>  0 pairs (X) / D4 = 3  => 18 pairs (_)
B7,C7: 4.. / B7 = 4  => 16 pairs (_) / C7 = 4  => 15 pairs (_)
H8,I8: 4.. / H8 = 4  => 19 pairs (_) / I8 = 4  =>  0 pairs (*)
B3,B7: 4.. / B3 = 4  => 15 pairs (_) / B7 = 4  => 16 pairs (_)
E2,E3: 5.. / E2 = 5  => 19 pairs (_) / E3 = 5  => 15 pairs (_)
G4,I4: 5.. / G4 = 5  => 16 pairs (_) / I4 = 5  =>  0 pairs (*)
B7,C7: 5.. / B7 = 5  => 15 pairs (_) / C7 = 5  => 16 pairs (_)
G8,I8: 5.. / G8 = 5  =>  0 pairs (*) / I8 = 5  =>  0 pairs (X)
C2,E2: 5.. / C2 = 5  => 15 pairs (_) / E2 = 5  => 19 pairs (_)
B3,B7: 5.. / B3 = 5  => 16 pairs (_) / B7 = 5  => 15 pairs (_)
G4,G8: 5.. / G4 = 5  => 16 pairs (_) / G8 = 5  =>  0 pairs (*)
I4,I8: 5.. / I4 = 5  =>  0 pairs (*) / I8 = 5  =>  0 pairs (X)
A2,A3: 6.. / A2 = 6  =>  0 pairs (X) / A3 = 6  => 21 pairs (_)
B4,C5: 6.. / B4 = 6  =>  0 pairs (*) / C5 = 6  =>  0 pairs (X)
E8,F9: 6.. / E8 = 6  =>  0 pairs (*) / F9 = 6  =>  0 pairs (X)
E1,I1: 6.. / E1 = 6  =>  0 pairs (X) / I1 = 6  =>  0 pairs (_)
B4,I4: 6.. / B4 = 6  =>  0 pairs (*) / I4 = 6  =>  0 pairs (X)
B8,E8: 6.. / B8 = 6  =>  0 pairs (X) / E8 = 6  =>  0 pairs (_)
C5,C9: 6.. / C5 = 6  =>  0 pairs (X) / C9 = 6  =>  0 pairs (_)
F2,F9: 6.. / F2 = 6  =>  0 pairs (*) / F9 = 6  =>  0 pairs (X)
D2,F2: 8.. / D2 = 8  => 18 pairs (_) / F2 = 8  =>  0 pairs (X)
B9,C9: 8.. / B9 = 8  => 22 pairs (_) / C9 = 8  =>  0 pairs (X)
A3,A6: 8.. / A3 = 8  =>  0 pairs (X) / A6 = 8  => 20 pairs (_)
D2,D4: 8.. / D2 = 8  => 18 pairs (_) / D4 = 8  =>  0 pairs (X)
G4,G8: 8.. / G4 = 8  =>  0 pairs (*) / G8 = 8  =>  0 pairs (X)
B4,C5: 9.. / B4 = 9  =>  0 pairs (X) / C5 = 9  =>  0 pairs (_)
H7,H9: 9.. / H7 = 9  =>  0 pairs (X) / H9 = 9  =>  0 pairs (_)
C5,F5: 9.. / C5 = 9  =>  0 pairs (*) / F5 = 9  =>  0 pairs (X)
A7,H7: 9.. / A7 = 9  =>  0 pairs (*) / H7 = 9  =>  0 pairs (X)
A2,A7: 9.. / A2 = 9  =>  0 pairs (X) / A7 = 9  =>  0 pairs (_)
* DURATION: 0:01:34.970143  START: 12:39:51.192836  END: 12:41:26.162979 2017-05-04
* CP COUNT: (43)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A6,A7,B3,B4,B7,B8,C5,C7,D2,D4,E8,F7,F9,G4,G8,H7,H8,H9)
* 7..2.415..1....7.....1.79..4.1....7.57.41.3.....675419...78.6.13.79.1...1..54.2.7
* PAIR B3: 4,5 BLK 1
C2: 4,5,2,3,9                            # reduction candidate for 4,5
C2: 4,5                                  # 19 pairs
C3: 4,5,2,3,8                            # reduction candidate for 4,5
C3: 4,5                                  # 20 pairs
* PAIR B4: 6,9 COL B
B9: 6,9,8                                # reduction candidate for 6,9
B9: 6,9 => CTR
* 7..2.415..1....7.....1.79..491....765764193.....6754199..782631327961..5168543297
B9: 8                                    # 22 pairs
* PAIR C5: 6,9 COL C
C9: 6,9,8                                # reduction candidate for 6,9
C9: 8 => CTR
* 7..2.415..1....7.....1.79..491....765764193.....6754199..782631327961..5168543297
C9: 6,9                                  # 22 pairs
* PAIR A6: 2,8 BLK 4
B6: 2,8,3                                # reduction candidate for 2,8
B6: 2,8                                  # 24 pairs
C6: 2,8,3                                # reduction candidate for 2,8
C6: 2,8 => SOLVED
* 798234156215896743643157928461329875579418362832675419954782631327961584186543297
C6: 3                                    # 24 pairs
* PAIR A6: 2,8 COL A
A3: 2,8,6                                # reduction candidate for 2,8
A3: 2,8 => CTR
* 7..2.415.61....7.....1.79..4.1....7.57.41.3.....6754199..782631327961...1..54.2.7
A3: 6                                    # 21 pairs
* PAIR G4: 5,8 BLK 6
I4: 5,8,2,6                              # reduction candidate for 5,8
I4: 5,8 => SOLVED
* 798234156215896743643157928461329875579418362832675419954782631327961584186543297
I4: 2,6                                  # 18 pairs
* PAIR A7: 2,9 COL A
A2: 2,9,6                                # reduction candidate for 2,9
A2: 6 => CTR
* 7..2.415.61....7.....1.79..4.1....7.57.41.3.....6754199..782631327961...1..54.2.7
A2: 2,9                                  # 21 pairs
* PAIR C7: 4,5 COL C
C2: 4,5,2,3,9                            # reduction candidate for 4,5
C2: 4,5                                  # 19 pairs
C3: 4,5,2,3,8                            # reduction candidate for 4,5
C3: 4,5                                  # 20 pairs
* PAIR G8: 5,8 BLK 9
I8: 5,8,4                                # reduction candidate for 5,8
I8: 4 => SOLVED
* 798234156215896743643157928461329875579418362832675419954782631327961584186543297
I8: 5,8                                  # 19 pairs
* PAIR H8: 4,8 BLK 9
I8: 4,8,5                                # reduction candidate for 4,8
I8: 4,8 => SOLVED
* 798234156215896743643157928461329875579418362832675419954782631327961584186543297
I8: 5                                    # 16 pairs
* PAIR H8: 4,8 COL H
H3: 4,8,2,6                              # reduction candidate for 4,8
H3: 4,8                                  # 21 pairs
H3: 2,6                                  # 21 pairs
* INCONCLUSIVE
* SAVE PR GRAPH xx-top500-285-base-pr-000.dot
* REASONING
* DIS # B9: 6,9 => CTR => B9: 8
* DIS # C9: 8 => CTR => C9: 6,9
* PRF # C6: 2,8 => SOL
* DIS # A3: 2,8 => CTR => A3: 6
* PRF # I4: 5,8 => SOL
* DIS # A2: 6 => CTR => A2: 2,9
* PRF # I8: 4 => SOL
* PRF # I8: 4,8 => SOL
* CNT   8 HDP CHAINS /  23 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A6,A7,B3,B4,B7,B8,C5,C7,D2,D4,E8,F7,F9,G4,G8,H7,H8,H9)
* 7..2.415..1....7.....1.79..4.1....7.57.41.3.....675419...78.6.13.79.1...1..54.2.7
* PAIR B3: 4,5 BLK 1
C2: 4,5,2,3,9                            # reduction candidate for 4,5
C2: 4,5                                  # 19 pairs
C3: 4,5,2,3,8                            # reduction candidate for 4,5
C3: 4,5                                  # 20 pairs
* PAIR B4: 6,9 COL B
B9: 6,9,8                                # reduction candidate for 6,9
B9: 6,9 => CTR
* 7..2.415..1....7.....1.79..491....765764193.....6754199..782631327961..5168543297
* PAIR RESTART
* PAIR A6: 2,8 BLK 4
C6: 2,8,3                                # reduction candidate for 2,8
C6: 2,8 => SOLVED
* 798234156215896743643157928461329875579418362832675419954782631327961584186543297
* DURATION: 0:00:07.369199  START: 12:41:55.100235  END: 12:42:02.469434 2017-05-04
* SOLUTION FOUND
* SAVE PR GRAPH xx-top500-285-base-pr-001.dot
* REASONING
* DIS # B9: 6,9 => CTR => B9: 8
* PRF B9: 8 # C6: 2,8 => SOL
* STA B9: 8 + C6: 2,8
* CNT   2 HDP CHAINS /   4 HYP OPENED

Header Info

Top 500 Minimum 17 285

solution: 798234156215896743643157928461329875579418362832675419954782631327961584186543297
info: 2332     FNBHWY   S8.f     7860

http://www.sfsudoku.com/su17ExtremeDiff500.txt from http://www.minimumsudoku.com/

Solution

position: 798234156215896743643157928461329875579418362832675419954782631327961584186543297 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 # C2: 4,5 => UNS
* INC # C3: 4,5 => UNS
* DIS # B9: 6,9 => CTR => B9: 8
* INC # B9: 8 => UNS
* INC # C9: 6,9 => UNS
* DIS # C9: 8 => CTR => C9: 6,9
* INC # B6: 2,8 => UNS
* PRF # C6: 2,8 => SOL
* INC # C6: 3 => UNS
* DIS # A3: 2,8 => CTR => A3: 6
* INC # A3: 6 => UNS
* PRF # I4: 5,8 => SOL
* INC # I4: 2,6 => UNS
* INC # A2: 2,9 => UNS
* DIS # A2: 6 => CTR => A2: 2,9
* INC # C2: 4,5 => UNS
* INC # C3: 4,5 => UNS
* INC # I8: 5,8 => UNS
* PRF # I8: 4 => SOL
* PRF # I8: 4,8 => SOL
* INC # I8: 5 => UNS
* INC # H3: 4,8 => UNS
* INC # H3: 2,6 => UNS
* CNT  23 HDP CHAINS /  23 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* INC # C2: 4,5 => UNS
* INC # C3: 4,5 => UNS
* DIS # B9: 6,9 => CTR => B9: 8
* PRF B9: 8 # C6: 2,8 => SOL
* STA B9: 8 + C6: 2,8
* CNT   4 HDP CHAINS /   4 HYP OPENED