Analysis of zz-sudoku-de-770757-base.sdk

Contents

Original Sudoku

level: medium

Original Sudoku

position: .2.4.7.5...8...4...1.5.3.8..36...71.5.......2.72...94..8.1.9.2...4...3...9.2.6.7. initial

Autosolve

position: .2.48715..58.124..41.5.328..36.2471554......2.72...94..8.1.9.2.264...391.9.2.6.7. autosolve
Autosolve

Pair Reduction Variants

Pair Reduction Analysis

Pair Reduction Analysis

The following important HDP chains were detected:

* DIS # A1: 3,9 => CTR => A1: 6
* DIS # I1: 6 => CTR => I1: 3,9
* DIS # A2: 3,6 => CTR => A2: 7,9
* DIS # I3: 7,9 => CTR => I3: 6
* PRF # I3: 6 => SOL
* PRF # A2: 6,9 => SOL
* DIS # A2: 3,7 => CTR => A2: 6,9
* DIS # I2: 6,9 => CTR => I2: 3,7
* DIS # D5: 6,9 => CTR => D5: 3,7,8
* DIS # I3: 7 => CTR => I3: 6,9
* DIS # E5: 6,9 => CTR => E5: 7
* PRF # E5: 7 => SOL
* DIS # I1: 3,6 => CTR => I1: 9
* DIS # I2: 3,6 => CTR => I2: 7,9
* DIS # A2: 3,6 => CTR => A2: 7,9
* DIS # F6: 1,8 => CTR => F6: 5
* PRF # F6: 5 => SOL
* DIS # D5: 8,9 => CTR => D5: 3,6,7
* DIS # F6: 1,8 => CTR => F6: 5
* PRF # F6: 5 => SOL
* DIS # I6: 6,8 => CTR => I6: 3
* PRF # I6: 3 => SOL
* DIS # D5: 6,8 => CTR => D5: 3,7,9
* PRF # I6: 3,6 => SOL
* DIS # I6: 8 => CTR => I6: 3,6
* PRF # D5: 3,6 => SOL
* DIS # D5: 7,8,9 => CTR => D5: 3,6
* DIS # C7: 3,7 => CTR => C7: 5
* PRF # C7: 5 => SOL
* DIS # A2: 3,7 => CTR => A2: 6,9
* PRF # A2: 6,9 => SOL
* PRF # C9: 1,3 => SOL
* DIS # C9: 5 => CTR => C9: 1,3
* DIS # D5: 7,8 => CTR => D5: 3,6,9
* PRF # D5: 3,6,9 => SOL
* PRF # F6: 5,8 => SOL
* DIS # F6: 1 => CTR => F6: 5,8
* CNT  37 HDP CHAINS /  49 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 # A1: 3,9 => CTR => A1: 6
* DIS A1: 6 # A2: 7 => CTR => A2: 3,9
* DIS A1: 6 + A2: 3,9 # D5: 6,9 => CTR => D5: 3,7,8
* DIS A1: 6 + A2: 3,9 + D5: 3,7,8 # E5: 6,9 => CTR => E5: 7
* PRF A1: 6 + A2: 3,9 + D5: 3,7,8 + E5: 7 => SOL
* STA A1: 6 + A2: 3,9 + D5: 3,7,8 + E5: 7
* CNT   5 HDP CHAINS /   6 HYP OPENED

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

Details

Positions

.2.4.7.5...8...4...1.5.3.8..36...71.5.......2.72...94..8.1.9.2...4...3...9.2.6.7. initial
.2.48715..58.124..41.5.328..36.2471554......2.72...94..8.1.9.2.264...391.9.2.6.7. autosolve
623487159958612437417593286836924715549371862172865943785139624264758391391246578 solved

Classification

level: medium

Pairing Analysis

--------------------------------------------------
* PAIRS (24)
C1: 3,9
C3: 7,9
D2: 6,9
E3: 6,9
H2: 3,6
A4: 8,9
C5: 1,9
A6: 1,8
D4: 8,9
F5: 1,8
E6: 5,6
G5: 6,8
H5: 3,6
A7: 3,7
A9: 1,3
E7: 3,4
D8: 7,8
E8: 5,7
F8: 5,8
E9: 3,4
G7: 5,6
I7: 4,6
G9: 5,8
I9: 4,8

--------------------------------------------------
* CONSTRAINT PAIRS (AUTO SOLVE)
C5,A6: 1.. / C5 = 1  =>  0 pairs (X) / A6 = 1  =>  0 pairs (_)
F5,F6: 1.. / F5 = 1  =>  0 pairs (*) / F6 = 1  =>  0 pairs (X)
A9,C9: 1.. / A9 = 1  =>  0 pairs (X) / C9 = 1  =>  0 pairs (_)
C5,F5: 1.. / C5 = 1  =>  0 pairs (X) / F5 = 1  =>  0 pairs (_)
A6,F6: 1.. / A6 = 1  =>  0 pairs (*) / F6 = 1  =>  0 pairs (X)
A6,A9: 1.. / A6 = 1  =>  0 pairs (*) / A9 = 1  =>  0 pairs (X)
C5,C9: 1.. / C5 = 1  =>  0 pairs (X) / C9 = 1  =>  0 pairs (_)
D5,D6: 3.. / D5 = 3  =>  0 pairs (*) / D6 = 3  =>  0 pairs (X)
H5,I6: 3.. / H5 = 3  =>  0 pairs (X) / I6 = 3  =>  0 pairs (_)
E7,E9: 3.. / E7 = 3  =>  0 pairs (*) / E9 = 3  =>  0 pairs (X)
D5,H5: 3.. / D5 = 3  =>  0 pairs (*) / H5 = 3  =>  0 pairs (X)
D6,I6: 3.. / D6 = 3  =>  0 pairs (X) / I6 = 3  =>  0 pairs (_)
H2,H5: 3.. / H2 = 3  =>  0 pairs (*) / H5 = 3  =>  0 pairs (X)
E7,E9: 4.. / E7 = 4  =>  0 pairs (X) / E9 = 4  =>  0 pairs (_)
I7,I9: 4.. / I7 = 4  =>  0 pairs (*) / I9 = 4  =>  0 pairs (X)
E7,I7: 4.. / E7 = 4  =>  0 pairs (X) / I7 = 4  =>  0 pairs (_)
E9,I9: 4.. / E9 = 4  =>  0 pairs (*) / I9 = 4  =>  0 pairs (X)
E6,F6: 5.. / E6 = 5  =>  0 pairs (X) / F6 = 5  =>  0 pairs (_)
C7,C9: 5.. / C7 = 5  =>  0 pairs (*) / C9 = 5  =>  0 pairs (X)
E8,F8: 5.. / E8 = 5  =>  0 pairs (*) / F8 = 5  =>  0 pairs (X)
G7,G9: 5.. / G7 = 5  =>  0 pairs (X) / G9 = 5  =>  0 pairs (_)
C7,G7: 5.. / C7 = 5  =>  0 pairs (*) / G7 = 5  =>  0 pairs (X)
C9,G9: 5.. / C9 = 5  =>  0 pairs (X) / G9 = 5  =>  0 pairs (_)
E6,E8: 5.. / E6 = 5  =>  0 pairs (X) / E8 = 5  =>  0 pairs (_)
F6,F8: 5.. / F6 = 5  =>  0 pairs (*) / F8 = 5  =>  0 pairs (X)
A1,A2: 6.. / A1 = 6  => 25 pairs (_) / A2 = 6  =>  0 pairs (X)
D2,E3: 6.. / D2 = 6  =>  0 pairs (*) / E3 = 6  =>  0 pairs (X)
G7,I7: 6.. / G7 = 6  =>  0 pairs (*) / I7 = 6  =>  0 pairs (X)
A1,I1: 6.. / A1 = 6  => 25 pairs (_) / I1 = 6  =>  0 pairs (X)
E3,I3: 6.. / E3 = 6  =>  0 pairs (X) / I3 = 6  =>  0 pairs (_)
G5,G7: 6.. / G5 = 6  =>  0 pairs (X) / G7 = 6  =>  0 pairs (_)
H2,H5: 6.. / H2 = 6  =>  0 pairs (X) / H5 = 6  =>  0 pairs (_)
A2,C3: 7.. / A2 = 7  =>  0 pairs (X) / C3 = 7  => 24 pairs (_)
I2,I3: 7.. / I2 = 7  => 24 pairs (_) / I3 = 7  =>  0 pairs (X)
D5,E5: 7.. / D5 = 7  =>  0 pairs (X) / E5 = 7  =>  0 pairs (_)
A7,C7: 7.. / A7 = 7  => 24 pairs (_) / C7 = 7  =>  0 pairs (X)
D8,E8: 7.. / D8 = 7  =>  0 pairs (*) / E8 = 7  =>  0 pairs (X)
A2,I2: 7.. / A2 = 7  =>  0 pairs (X) / I2 = 7  => 24 pairs (_)
C3,I3: 7.. / C3 = 7  => 24 pairs (_) / I3 = 7  =>  0 pairs (X)
A2,A7: 7.. / A2 = 7  =>  0 pairs (X) / A7 = 7  => 24 pairs (_)
C3,C7: 7.. / C3 = 7  => 24 pairs (_) / C7 = 7  =>  0 pairs (X)
D5,D8: 7.. / D5 = 7  =>  0 pairs (X) / D8 = 7  =>  0 pairs (_)
E5,E8: 7.. / E5 = 7  =>  0 pairs (*) / E8 = 7  =>  0 pairs (X)
A4,A6: 8.. / A4 = 8  =>  0 pairs (*) / A6 = 8  =>  0 pairs (X)
G5,I6: 8.. / G5 = 8  =>  0 pairs (*) / I6 = 8  =>  0 pairs (X)
D8,F8: 8.. / D8 = 8  =>  0 pairs (X) / F8 = 8  =>  0 pairs (_)
G9,I9: 8.. / G9 = 8  =>  0 pairs (X) / I9 = 8  =>  0 pairs (_)
A4,D4: 8.. / A4 = 8  =>  0 pairs (*) / D4 = 8  =>  0 pairs (X)
G5,G9: 8.. / G5 = 8  =>  0 pairs (*) / G9 = 8  =>  0 pairs (X)
I6,I9: 8.. / I6 = 8  =>  0 pairs (X) / I9 = 8  =>  0 pairs (_)
D2,E3: 9.. / D2 = 9  =>  0 pairs (X) / E3 = 9  =>  0 pairs (_)
A4,C5: 9.. / A4 = 9  =>  0 pairs (X) / C5 = 9  =>  0 pairs (_)
A4,D4: 9.. / A4 = 9  =>  0 pairs (X) / D4 = 9  =>  0 pairs (_)
E3,E5: 9.. / E3 = 9  =>  0 pairs (*) / E5 = 9  =>  0 pairs (X)
* DURATION: 0:01:27.715094  START: 08:39:45.599587  END: 08:41:13.314681 2017-05-01
* CP COUNT: (54)
* SOLUTION FOUND

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A4,A6,A7,A9,C1,C3,C5,D2,D4,D8,E3,E6,E7,E8,E9,F5,F8,G5,G7,G9,H2,H5,I7,I9)
* .2.48715..58.124..41.5.328..36.2471554......2.72...94..8.1.9.2.264...391.9.2.6.7.
* PAIR C1: 3,9 BLK 1
A1: 3,9,6                                # reduction candidate for 3,9
A1: 3,9 => CTR
* .2.487156658912437417563289936824715541.....2.72...94..8.1.9.2.264...391.9.2.6.7.
A1: 6                                    # 25 pairs
A2: 3,9,6,7                              # reduction candidate for 3,9
A2: 3,9                                  # 26 pairs
* PAIR C1: 3,9 ROW 1
I1: 3,9,6                                # reduction candidate for 3,9
I1: 6 => CTR
* .2.487156658912437417563289936824715541.....2.72...94..8.1.9.2.264...391.9.2.6.7.
I1: 3,9                                  # 25 pairs
* PAIR C3: 7,9 BLK 1
A2: 7,9,3,6                              # reduction candidate for 7,9
A2: 3,6 => CTR
* .2.48715..589124.7417563289936824715541.....2.72...94.78.1.9.2.264...391.9.2.6.7.
A2: 7,9                                  # 27 pairs
* PAIR C3: 7,9 ROW 3
I3: 7,9,6                                # reduction candidate for 7,9
I3: 7,9 => CTR
* .2.48715..58.124..41.56328..36.2471554..9...2.72.5.94..8.1.9.2.264.75391.9.2.6.7.
I3: 6 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
* PAIR D2: 6,9 ROW 2
A2: 6,9,3,7                              # reduction candidate for 6,9
A2: 6,9 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
A2: 3,7 => CTR
* 62.48715..58.124..41.5.328.936824715541.....2.72...94..8.1.9.2.264...391.9.2.6.7.
I2: 6,9,3,7                              # reduction candidate for 6,9
I2: 6,9 => CTR
* .2.48715.758.1243.419563287936824715541.....2.72...94..8.1.9.2.264...391.9.2.6.7.
I2: 3,7                                  # 25 pairs
* PAIR D2: 6,9 COL D
D5: 6,9,3,7,8                            # reduction candidate for 6,9
D5: 6,9 => CTR
* .2.48715..58.1246.41.5.328..36.2471554..7..32.723..94..8.1.9.2.264758391.9.2.6.7.
D5: 3,7,8                                # 24 pairs
* PAIR E3: 6,9 ROW 3
I3: 6,9,7                                # reduction candidate for 6,9
I3: 7 => CTR
* .2.48715..58.124..41.563287.36.2471554..9...2.72.5.94..871.9526264.75391.952.6874
I3: 6,9                                  # 24 pairs
* PAIR E3: 6,9 COL E
E5: 6,9,7                                # reduction candidate for 6,9
E5: 6,9 => CTR
* .2.48715..586124..41.5.328..36.2471554.7...32.723..94..8.1.9.2.264875391.9.2.6.7.
E5: 7 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
* PAIR H2: 3,6 BLK 3
I1: 3,6,9                                # reduction candidate for 3,6
I1: 3,6 => CTR
* .2.48715..58.124.74175.3289.36.2471554..9...2.72...94.78.1.9.2.264.75391.9.2.6.7.
I1: 9                                    # 27 pairs
I2: 3,6,7,9                              # reduction candidate for 3,6
I2: 3,6 => CTR
* .2.48715.7589124..419563287936824715541.....2.72...94..8.1.9.2.264...391.9.2.6.7.
I2: 7,9                                  # 25 pairs
* PAIR H2: 3,6 ROW 2
A2: 3,6,7,9                              # reduction candidate for 3,6
A2: 3,6 => CTR
* .2.48715..589124.7417563289936824715541.....2.72...94.78.1.9.2.264...391.9.2.6.7.
A2: 7,9                                  # 27 pairs
* PAIR A6: 1,8 ROW 6
F6: 1,8,5                                # reduction candidate for 1,8
F6: 1,8 => CTR
* 62.48715..586124..41.5.328..36.2471554.7...32.7235.946.8.1.9624264875391.9.246578
F6: 5 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
* PAIR D4: 8,9 BLK 5
D5: 8,9,3,6,7                            # reduction candidate for 8,9
D5: 8,9 => CTR
* .2.48715..586124..41.5.328..36.2471554..7..32.72365948.8.1.9.2.264758391.9.2.6874
D5: 3,6,7                                # 24 pairs
* PAIR F5: 1,8 BLK 5
F6: 1,8,5                                # reduction candidate for 1,8
F6: 1,8 => CTR
* 62.48715..586124..41.5.328..36.2471554.7...32.7235.946.8.1.9624264875391.9.246578
F6: 5 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
* PAIR G5: 6,8 BLK 6
I6: 6,8,3                                # reduction candidate for 6,8
I6: 6,8 => CTR
* .2.48715..58.1246.41.56328..36.2471554.6...32.723..94..8.1.9.2.264...391.9.2.6.7.
I6: 3 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
* PAIR G5: 6,8 ROW 5
D5: 6,8,3,7,9                            # reduction candidate for 6,8
D5: 6,8 => CTR
* .2.48715..58.1246.41.5.328..36.2471554..7..32.723..94..8.1.9.2.264758391.9.2.6.7.
D5: 3,7,9                                # 24 pairs
* PAIR H5: 3,6 BLK 6
I6: 3,6,8                                # reduction candidate for 3,6
I6: 3,6 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
I6: 8 => CTR
* .2.48715..586124..41.5.328..36.2471554.....32.72365948.8.1.9.2.264.58391.9.2.6874
* PAIR H5: 3,6 ROW 5
D5: 3,6,7,8,9                            # reduction candidate for 3,6
D5: 3,6 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
D5: 7,8,9 => CTR
* .2.48715..586124..41.5.328..36.2471554.....32.723..94..8.1.9.2.264...391.9.2.6.7.
* PAIR A7: 3,7 BLK 7
C7: 3,7,5                                # reduction candidate for 3,7
C7: 3,7 => CTR
* 62.48715..58.1246.41.56328..36.24715541.98..2.72...94..8.1.9526264...391.952.6874
C7: 5 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
* PAIR A7: 3,7 COL A
A2: 3,7,6,9                              # reduction candidate for 3,7
A2: 3,7 => CTR
* 62.48715..58.124..41.5.328.936824715541.....2.72...94..8.1.9.2.264...391.9.2.6.7.
A2: 6,9 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
* PAIR A9: 1,3 BLK 7
C9: 1,3,5                                # reduction candidate for 1,3
C9: 1,3 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
C9: 5 => CTR
* .2.48715..58.124..41.5.328..36.24715541..8632872...94..8.1.9.2.264...391.9.2.6.7.
* PAIR D8: 7,8 COL D
D5: 7,8,3,6,9                            # reduction candidate for 7,8
D5: 7,8 => CTR
* .2.48715..586124..41.5.328..36.2471554.....32.723..94..8.1.9.2.264...391.9.2.6.7.
D5: 3,6,9 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
* PAIR F8: 5,8 COL F
F6: 5,8,1                                # reduction candidate for 5,8
F6: 5,8 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
F6: 1 => CTR
* .2.48715..58.124..41.5.328..36.24715541798..2.72.5194..8.1.9.2.264.7539119.2.6.7.
* INCONCLUSIVE
* SAVE PR GRAPH zz-sudoku-de-770757-base-pr-000.dot
* REASONING
* DIS # A1: 3,9 => CTR => A1: 6
* DIS # I1: 6 => CTR => I1: 3,9
* DIS # A2: 3,6 => CTR => A2: 7,9
* DIS # I3: 7,9 => CTR => I3: 6
* PRF # I3: 6 => SOL
* PRF # A2: 6,9 => SOL
* DIS # A2: 3,7 => CTR => A2: 6,9
* DIS # I2: 6,9 => CTR => I2: 3,7
* DIS # D5: 6,9 => CTR => D5: 3,7,8
* DIS # I3: 7 => CTR => I3: 6,9
* DIS # E5: 6,9 => CTR => E5: 7
* PRF # E5: 7 => SOL
* DIS # I1: 3,6 => CTR => I1: 9
* DIS # I2: 3,6 => CTR => I2: 7,9
* DIS # A2: 3,6 => CTR => A2: 7,9
* DIS # F6: 1,8 => CTR => F6: 5
* PRF # F6: 5 => SOL
* DIS # D5: 8,9 => CTR => D5: 3,6,7
* DIS # F6: 1,8 => CTR => F6: 5
* PRF # F6: 5 => SOL
* DIS # I6: 6,8 => CTR => I6: 3
* PRF # I6: 3 => SOL
* DIS # D5: 6,8 => CTR => D5: 3,7,9
* PRF # I6: 3,6 => SOL
* DIS # I6: 8 => CTR => I6: 3,6
* PRF # D5: 3,6 => SOL
* DIS # D5: 7,8,9 => CTR => D5: 3,6
* DIS # C7: 3,7 => CTR => C7: 5
* PRF # C7: 5 => SOL
* DIS # A2: 3,7 => CTR => A2: 6,9
* PRF # A2: 6,9 => SOL
* PRF # C9: 1,3 => SOL
* DIS # C9: 5 => CTR => C9: 1,3
* DIS # D5: 7,8 => CTR => D5: 3,6,9
* PRF # D5: 3,6,9 => SOL
* PRF # F6: 5,8 => SOL
* DIS # F6: 1 => CTR => F6: 5,8
* CNT  37 HDP CHAINS /  49 HYP OPENED

--------------------------------------------------
* PREPARE PR GRAPH
* PAIR REDUCTION ..
* LEVEL 0 PASS 1 ROUND 1 (AUTO SOLVE) (A4,A6,A7,A9,C1,C3,C5,D2,D4,D8,E3,E6,E7,E8,E9,F5,F8,G5,G7,G9,H2,H5,I7,I9)
* .2.48715..58.124..41.5.328..36.2471554......2.72...94..8.1.9.2.264...391.9.2.6.7.
* PAIR C1: 3,9 BLK 1
A1: 3,9,6                                # reduction candidate for 3,9
A1: 3,9 => CTR
* .2.487156658912437417563289936824715541.....2.72...94..8.1.9.2.264...391.9.2.6.7.
A2: 3,9,7                                # reduction candidate for 3,9
A2: 3,9                                  # 26 pairs
* RESTART
* PAIR C1: 3,9 BLK 1
A2: 3,9,7                                # reduction candidate for 3,9
A2: 7 => CTR
* 6234871597589124..419563287936824715541.....2.72...94..8.1.9.2.264...391.9.2.6.7.
* PAIR D2: 6,9 COL D
D5: 6,9,3,7,8                            # reduction candidate for 6,9
D5: 6,9 => CTR
* 62.48715335891246741756328..36.2471554..7..32.723..94.78.1.9.2.264758391.9.2.6.7.
* PAIR RESTART
* PAIR E3: 6,9 COL E
E5: 6,9,7                                # reduction candidate for 6,9
E5: 6,9 => CTR
* 62.487153358.124.74175.328..36.2471554.7...32.723..94.78.1.9.2.264875391.9.2.6.7.
E5: 7 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
* DURATION: 0:00:08.414130  START: 08:41:59.650337  END: 08:42:08.064467 2017-05-01
* SOLUTION FOUND
* SAVE PR GRAPH zz-sudoku-de-770757-base-pr-001.dot
* REASONING
* DIS # A1: 3,9 => CTR => A1: 6
* DIS A1: 6 # A2: 7 => CTR => A2: 3,9
* DIS A1: 6 + A2: 3,9 # D5: 6,9 => CTR => D5: 3,7,8
* DIS A1: 6 + A2: 3,9 + D5: 3,7,8 # E5: 6,9 => CTR => E5: 7
* PRF A1: 6 + A2: 3,9 + D5: 3,7,8 + E5: 7 => SOL
* STA A1: 6 + A2: 3,9 + D5: 3,7,8 + E5: 7
* CNT   5 HDP CHAINS /   6 HYP OPENED

Header Info

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level: medium

* PAIR REDUCTION ..
* ROUND 1: .2.48715..58.124..41.5.328..36.2471554......2.72...94..8.1.9.2.264...391.9.2.6.7.
C1: 3,9
A1: 3,6,9                                # reduction candidate for 3,9
A1: 3,9 => CTR
* .2.487156658912437417563289936824715541.....2.72...94..8.1.9.2.264...391.9.2.6.7.
A2: 3,7,9                                # reduction candidate for 3,9
A2: 7 => CTR
* 6234871597589124..419563287936824715541.....2.72...94..8.1.9.2.264...391.9.2.6.7.
D2: 6,9
D5: 3,6,7,8,9                            # reduction candidate for 6,9
D5: 6,9 => CTR
* 62.48715335891246741756328..36.2471554..7..32.723..94.78.1.9.2.264758391.9.2.6.7.
E3: 6,9
E5: 6,7,9                                # reduction candidate for 6,9
E5: 6,9 => CTR
* 62.487153358.124.74175.328..36.2471554.7...32.723..94.78.1.9.2.264875391.9.2.6.7.
E5: 7 => SOLVED
* 623487159958612437417593286836924715549371862172865943785139624264758391391246578
* SOLVED!
--------------------------------------------------

xy-wing
C5: 1,9
D4: 8,9
F5: 1,8
* DISABLE VALUE:: E5 != 9

step 01

D4: 8,9
A4: 8,9
F5: 1,8

C5: 1,9

D4 = 8 => F5 = 1 => C5 = 9
D4 = 8 => A4 = 9 => CTR!
=> D4 != 8

* DISABLE VALUE:: D4 != 8
D4: 9                 # naked single
* DISABLE VALUE:: A4 != 9
A4: 8                 # naked single
* DISABLE VALUE:: A6 != 8
A6: 1                 # naked single
* DISABLE VALUE:: C5 != 1
C5: 9                 # naked single
* DISABLE VALUE:: F5 != 8
F5: 1                 # naked single

step 02

Solution

position: 623487159958612437417593286836924715549371862172865943785139624264758391391246578 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:

* DIS # A1: 3,9 => CTR => A1: 6
* INC # A1: 6 => UNS
* INC # A2: 3,9 => UNS
* INC # I1: 3,9 => UNS
* DIS # I1: 6 => CTR => I1: 3,9
* INC # A2: 7,9 => UNS
* DIS # A2: 3,6 => CTR => A2: 7,9
* DIS # I3: 7,9 => CTR => I3: 6
* PRF # I3: 6 => SOL
* PRF # A2: 6,9 => SOL
* DIS # A2: 3,7 => CTR => A2: 6,9
* DIS # I2: 6,9 => CTR => I2: 3,7
* INC # I2: 3,7 => UNS
* DIS # D5: 6,9 => CTR => D5: 3,7,8
* INC # D5: 3,7,8 => UNS
* INC # I3: 6,9 => UNS
* DIS # I3: 7 => CTR => I3: 6,9
* DIS # E5: 6,9 => CTR => E5: 7
* PRF # E5: 7 => SOL
* DIS # I1: 3,6 => CTR => I1: 9
* INC # I1: 9 => UNS
* DIS # I2: 3,6 => CTR => I2: 7,9
* INC # I2: 7,9 => UNS
* DIS # A2: 3,6 => CTR => A2: 7,9
* INC # A2: 7,9 => UNS
* DIS # F6: 1,8 => CTR => F6: 5
* PRF # F6: 5 => SOL
* DIS # D5: 8,9 => CTR => D5: 3,6,7
* INC # D5: 3,6,7 => UNS
* DIS # F6: 1,8 => CTR => F6: 5
* PRF # F6: 5 => SOL
* DIS # I6: 6,8 => CTR => I6: 3
* PRF # I6: 3 => SOL
* DIS # D5: 6,8 => CTR => D5: 3,7,9
* INC # D5: 3,7,9 => UNS
* PRF # I6: 3,6 => SOL
* DIS # I6: 8 => CTR => I6: 3,6
* PRF # D5: 3,6 => SOL
* DIS # D5: 7,8,9 => CTR => D5: 3,6
* DIS # C7: 3,7 => CTR => C7: 5
* PRF # C7: 5 => SOL
* DIS # A2: 3,7 => CTR => A2: 6,9
* PRF # A2: 6,9 => SOL
* PRF # C9: 1,3 => SOL
* DIS # C9: 5 => CTR => C9: 1,3
* DIS # D5: 7,8 => CTR => D5: 3,6,9
* PRF # D5: 3,6,9 => SOL
* PRF # F6: 5,8 => SOL
* DIS # F6: 1 => CTR => F6: 5,8
* CNT  49 HDP CHAINS /  49 HYP OPENED

A2. Pair Reduction

Full list of HDP chains traversed:

* DIS # A1: 3,9 => CTR => A1: 6
* INC A1: 6 # A2: 3,9 => UNS
* INC A1: 6 # A2: 3,9 => UNS
* DIS A1: 6 # A2: 7 => CTR => A2: 3,9
* DIS A1: 6 + A2: 3,9 # D5: 6,9 => CTR => D5: 3,7,8
* DIS A1: 6 + A2: 3,9 + D5: 3,7,8 # E5: 6,9 => CTR => E5: 7
* PRF A1: 6 + A2: 3,9 + D5: 3,7,8 + E5: 7 => SOL
* STA A1: 6 + A2: 3,9 + D5: 3,7,8 + E5: 7
* CNT   7 HDP CHAINS /   6 HYP OPENED