Sudoku strategies explained with graphics

Strategies


Overview Singles Naked Pairs Naked Triples Hidden Pairs Hidden Triples Naked Quads Hidden Quads Pointing Pair Pointing Triple Box Reduction X-Wing Finned X-Wing Sashimi Finned X-Wing Franken X-Wing Finned Mutant X-Wing Skyscraper Chute Remote Pairs Simple Coloring Y-Wing W-Wing Swordfish Finned Swordfish Sashimi Finned Swordfish Franken Swordfish Mutant Swordfish Finned Mutant Swordfish Sashimi Finned Mutant Swordfish Sue De Coq XYZ-Wing X-Cycle Bi-Value Universal Grave XY-Chain 3D Medusa Jellyfish Jellyfish Jellyfish Avoidable Rectangle Unique Rectangle Hidden Unique Rectangle WXYZ-Wing Firework Subset Exclusion Empty Rectangle Sue De Coq Extended SK Loop Exocet Almost Locked Sets Alternating Inference Chain Digit Forcing Chains Nishio Forcing Chains Cell Forcing Chains Unit Forcing Chains Almost Locked Sets Forcing Chain Death Blossom Pattern Overlay Bowman Bingo



Sudoku strategies at a glance

Naked Pairs

Naked Pair

Detailed explanation

Naked Triples

Naked Triple

Detailed explanation

Hidden Pairs

Hidden Pair

Detailed explanation

Hidden Triples

Hidden Triple

Detailed explanation

Naked Quads

Naked Quad

Detailed explanation

Hidden Quads

Hidden Quad

Detailed explanation

Pointing Pair

Pointing Pair

Detailed explanation

Pointing Triple

Pointing Triple

Detailed explanation

Box Reduction

Box Reduction

Detailed explanation

Finned X-Wing

Finned X-Wing

Detailed explanation

Sashimi Finned X-Wing

Sashimi Finned X-Wing

Detailed explanation

Franken X-Wing

Illustration not available, sorry.

Detailed explanation

Finned Mutant X-Wing

Finned RCCB Mutant X-Wing

Finned RCCB Mutant X-Wing

 

Finned CBRC Mutant X-Wing

Finned CBRC Mutant X-Wing

Detailed explanation

Chute Remote Pairs

Chute Remote Pairs

Detailed explanation

Simple Coloring

Twice in a unit:

Simple Coloring

 

Sees two different colors:

Simple Coloring

Detailed explanation

Finned Swordfish

Finned Swordfish

Detailed explanation

Sashimi Finned Swordfish

Sashimi Finned Swordfish

Detailed explanation

Franken Swordfish

CCBRRR Franken Swordfish

Illustration not available, sorry. If you have an example, I'd be very grateful to you if you sent it to sudokucoach@gmail.com.

 

RRRCCB Franken Swordfish

Illustration not available, sorry. If you have an example, I'd be very grateful to you if you sent it to sudokucoach@gmail.com.

Detailed explanation

Mutant Swordfish

RCBRCB Mutant Swordfish

Illustration not available, sorry. If you have an example, I'd be very grateful to you if you sent it to sudokucoach@gmail.com.

 

RCCRBB Mutant Swordfish

Illustration not available, sorry.

 

RBBRCC Mutant Swordfish

Illustration not available, sorry.

Detailed explanation

Finned Mutant Swordfish

Finned RCBRCB Mutant Swordfish

Illustration not available, sorry. If you have an example, I'd be very grateful to you if you sent it to sudokucoach@gmail.com.

 

Finned RCCRRB Mutant Swordfish

Illustration not available, sorry. If you have an example, I'd be very grateful to you if you sent it to sudokucoach@gmail.com.

 

Finned RCCRBB Mutant Swordfish

Illustration not available, sorry. If you have an example, I'd be very grateful to you if you sent it to sudokucoach@gmail.com.

 

Finned CCBRRB Mutant Swordfish

Illustration not available, sorry. If you have an example, I'd be very grateful to you if you sent it to sudokucoach@gmail.com.

 

Finned RRBCCB Mutant Swordfish

Illustration not available, sorry. If you have an example, I'd be very grateful to you if you sent it to sudokucoach@gmail.com.

 

Finned RCCBBB Mutant Swordfish

Illustration not available, sorry. If you have an example, I'd be very grateful to you if you sent it to sudokucoach@gmail.com.

 

Finned BBBRCC Mutant Swordfish

Illustration not available, sorry. If you have an example, I'd be very grateful to you if you sent it to sudokucoach@gmail.com.

Detailed explanation

Sashimi Finned Mutant Swordfish

RCCRBB Sashimi Finned Mutant Swordfish

Illustration not available, sorry. If you have an example, I'd be very grateful to you if you sent it to sudokucoach@gmail.com.

Detailed explanation

Sue De Coq (basic)

Sue De Coq Type 1:

X-Cycle

 

Sue De Coq Type 2:

X-Cycle

Detailed explanation

X-Cycle

Nice Loop:

X-Cycle

 

Discontinuity with weak links:

X-Cycle

 

Discontinuity with strong links:

X-Cycle

Detailed explanation

Bi-Value Universal Grave

Bi-Value Universal Grave

Detailed explanation

3D-Medusa

Same color twice in a Cell:

3D-Medusa

 

Same color twice in a Unit:

3D-Medusa

 

Two colors in a Cell:

3D-Medusa

 

Sees two different colors:

3D-Medusa

 

Unit-Cell elimination:

3D-Medusa

 

Emptying a Cell:

3D-Medusa

Detailed explanation

Finned Jellyfish

Jellyfish

Detailed explanation

Sashimi Finned Jellyfish

Jellyfish

Detailed explanation

Avoidable Rectangle

Avoidable Rectangle Type 1:

Avoidable Rectangle Type 1

 

Avoidable Rectangle Type 2:

Avoidable Rectangle Type 2

 

Detailed explanation

Unique Rectangle

Unique Rectangle Type 1:

Unique Rectangle

 

Unique Rectangle Type 2:

Unique Rectangle

 

Unique Rectangle Type 3:

Unique Rectangle

 

Extended Unique Rectangle:

Unique Rectangle

Detailed explanation

Hidden Unique Rectangle

Hidden Unique Rectangle Type 1:

Unique Rectangle

 

Hidden Unique Rectangle Type 2:

Unique Rectangle

 

Hidden Unique Rectangle Type 3:

Unique Rectangle

Detailed explanation

Firework

Triple Firework:

Unique Rectangle

 

Quadruple Firework:

Unique Rectangle

 

W-wing Firework:

Unique Rectangle

 

L-wing Firework:

Unique Rectangle

 

ALS-wing Firework:

Unique Rectangle

Detailed explanation

Subset Exclusion

Subset Exclusion

Detailed explanation

Empty Rectangle

Empty Rectangle

Detailed explanation

Sue De Coq Extended

Sue De Coq Extended (Type 1):

X-Cycle

 

Sue De Coq Extended (Type 2):

X-Cycle

Detailed explanation

SK Loop

SKL (classical)

SK Loop

 

Variant SK Loop with single, double and/or triple links

SK Loop with single, double and triple links

 

Variant SK Loop with solved Cells

SK Loop with solved Cells

Detailed explanation

Exocet

Rule 2:

Exocet - rule 2

 

Rule 3:

Exocet - rule 3

 

Rule 4:

Exocet - rule 4

 

Rule 5:

Exocet - rule 5

 

Rule 6:

Exocet - rule 6

 

Rule 7:

Exocet - rule 7

 

Rule 8:

Exocet - rule 8

 

Rule 9:

Exocet - rule 9

 

Rule 10:

Exocet - rule 10

 

Rule 11:

Exocet - rule 11

 

Exocet - rule 11

 

Rule 12:

Exocet - rule 12

 

Incompatible Pairs:

Exocet - Incompatible Pairs

Detailed explanation

Almost Locked Sets

Almost Locked Sets (Type 1):

Almost Locked Sets Type 1

 

Almost Locked Sets (Type 2):

Almost Locked Sets Type 2

Detailed explanation

Alternate Inference Chain

Nice loop:

Alternate Inference Chain

 

Discontinuity with weak links:

Alternate Inference Chain

 

Discontinuity with strong links:

Alternate Inference Chain

Detailed explanation

Digit Forcing Chains

Always "ON":

Digit Forcing Chains

 

Always "OFF":

Digit Forcing Chains

 

Two candidates "ON" in a Cell:

Digit Forcing Chains

 

Two candidates "ON" in a Unit:

Digit Forcing Chains

Detailed explanation

Nishio Forcing Chains

Same candidate both "ON" and "OFF":

Nishio Forcing Chains

 

Emptying a Cell:

Nishio Forcing Chains

 

Twice "ON" in a Unit:

Nishio Forcing Chains

 

Emptying a Unit

Nishio Forcing Chains

Detailed explanation

Cell Forcing Chains

Always "ON":

Cell Forcing Chains

 

Always "OFF":

Cell Forcing Chains

 

Same candidate both "ON" and "OFF":

Cell Forcing Chains

 

Some candidates "ON" in a region:

Cell Forcing Chains

Detailed explanation

Unit Forcing Chains

Always "ON":

Digit Forcing Chains

 

Always "OFF":

Unit Forcing Chains


 

Some candidates "ON" in a Cell:

Cell Forcing Chains

 

Some candidates "ON" in a region:

Cell Forcing Chains

Detailed explanation

Almost Locked Set Forcing Chain

Almost Locked Set Forcing Chain

Detailed explanation

Death Blossom

Death Blossom

Detailed explanation

Pattern Overlay

Pattern Overlay

Pattern Overlay

Detailed explanation

Bowman's Bingo

Bowman's Bingo

Detailed explanation