Advanced sudoku strategies https://www.sudoku9981.com/sudoku-solving/ These are the strategies used to solve a Sudoku. There are many different solving sudoku strategies discovered .Solving sudoku puzzles is easier than it looks.Learn more bout sudoku puzzles and how to solve them at Sudoku9981.com en-us sudoku9981 mirabyte Feed Writer 1.0 Sudoku Strategy Advanced Sudoku Strategies - Content https://www.sudoku9981.com/sudoku-solving/ Sun, 29 Apr 2007 21:22:08 +0800 https://www.sudoku9981.com/sudoku/2007/05/06/content Advanced Sudoku Strategies - Coloring Coloring is a single-digit solving technique that uses colors to mark the parity of candidates.

Although it is an advanced solving technique, many player know how to use it because it is supported by the popular Simple Sudoku program.

Simple Colors
Uses only 2 colors to form a single color cluster.
Multi-Colors | Supercoloring
Uses multiple colors (4, 6 or a higher multiple of 2) to form multiple color clusters.
Weak Colors
Extends Simple-Colors by the use of hinge linkages.
X-Colors
Uses only 2 colors, but also takes the implications for each color into account.
Color Trap
A technique that uses a single cluster to eliminate candidates outside the cluster.
Color Wrap
A technique that uses a single cluster to detect a contradiction in one of the colors.
Color Wing
A technique that uses multiple clusters to eliminate candidates outside these clusters. Same as Multi-Colors.
3D Medusa Coloring | Advanced Coloring
A set of techniques that uses colors on multiple digits. ]]> https://www.sudoku9981.com/sudoku-solving/Coloring.asp Sun, 29 Apr 2007 21:22:08 +0800 https://www.sudoku9981.com/sudoku/2007/05/06/color Advanced Sudoku Strategies - Fish The term fish is now accepted by most players as a name for all single-digit solving techniques which eliminate candidates by comparing sets of rows and columns.

Aliases are seafood and sealife.

Not all sizes of fish were discovered at the same time. Size 2 was already familiar to many players before they realized that the same trick could also be performed with more than 2 rows and columns. Here is a list of names given to fish of different sizes. They are often seen as different solving techniques. The term Swordfish has also been in use for all types of fish with more than 2 rows or columns.

X-Wing
2 rows vs. 2 columns
Swordfish
3 rows vs. 3 columns
Jellyfish
4 rows vs. 4 columns
Squirmbag
5 rows vs. 5 columns
Finned Fish
Fish patterns with additional candidates in a single box.
Sashimi Fish
Incomplete basic fish patterns with a fin.
Franken Fish
Fish patterns that include box constraints.
Mutant Fish
Fish patterns with mixed sets of constraints.
Kraken Fish
A fish pattern with indirect connections to a candidate which can be eliminated. ]]> https://www.sudoku9981.com/sudoku-solving/fish.asp Sun, 29 Apr 2007 21:22:08 +0800 https://www.sudoku9981.com/sudoku/2007/05/06/fish Advanced Sudoku Strategies - Chains and Loops Forcing Chain
Generic term for any type of chain.
X-Chain
Single digit chain of cells.
XY-Chain
Chain of bivalue cells.
Remote Pairs
Simplified form of XY-Chain, involving only two digits.
Fishy Cycle| X-Cycle
Single digit continuous loop.
Broken Wing
Eliminations caused by loops of odd length.
Nice Loops
Several types of loops formed by cells following strict rules and a notation system.
Double Implication Chain| DIC
There are 2 interpretations circulating. The first originates from a reliable source [1].
A Forcing Chain that has implications in both directions.
2 Forcing Chains starting from a bivalue cell or a bilocal unit showing a verity.
Alternating Inference Chain| AIC
A chain where each node is a candidate, with alternating strong and weak inference.
]]> https://www.sudoku9981.com/sudoku-solving/Chains-Loops.asp Sun, 29 Apr 2007 21:22:08 +0800 https://www.sudoku9981.com/sudoku/2007/05/06/chains Solving Sudoku Strategy - Singles Elementary solving technique, using the fact that only a single candidate is left for a constraint.

Singles are often ignored when players communicate about the way they solve a Sudoku. Singles are the only solving techniques which deal with immediate placements. Other techniques can only accomplish eliminations, but may lead to an immediate single.

Full House
A house with a single empty cell.
Last Digit
The last instance of a digit.
Hidden Single | Pinned Digit
A single candidate remaining for a digit in a house.
Naked Single | Forced Digit | Sole Candidate
A single candidate remaining in a cell.
]]> https://www.sudoku9981.com/sudoku-solving/single.asp Sun, 29 Apr 2007 21:22:08 +0800 https://www.sudoku9981.com/sudoku/2007/05/06/single Solving Sudoku Strategy - Intersections A part of the grid where 2 houses share one or more cells. Mostly used for intersections between a box and a row or column.

In standard Sudoku, there are 27 box-row intersections and 27 box-column intersections, each containing 3 cells.

Several Sudoku Variations have additional intersections between the extra houses and the lines and boxes.

Locked Candidates| Intersection Removal | Line-Box Interaction | Pointing (Pair, Triple) | Claiming
Candidates are locked in the intersection of a line and a box.
Locked Pair
A Naked Pair located in a single intersection.
Locked Triple
A Naked Triple located in a single intersection.
Almost Locked Candidates
A box-line intersection where the line or the box contains an Almost Locked Set, and the remaining cells in the line or box outside the intersection does not contain digits from the Almost Locked Set. ]]> https://www.sudoku9981.com/sudoku-solving/Intersections.asp Sun, 29 Apr 2007 21:22:08 +0800 https://www.sudoku9981.com/sudoku/2007/05/06/intersection Solving Sudoku Strategy - Subsets Complex problems can often be solved by finding ways to split them into several smaller problems. In a Sudoku, each house is a problem that has 362880 possible solutions (the possible permutations for the 9 digits). To reduce this number, a player will try to isolate groups of cells and digits from the remainder of the house.

When N cells and N digits are isolated, a subset of size N is formed.

Alternative terms are disjoint subset, locked set and number chain.

Naked Pair
2 cells with candidates for 2 digits.
Naked Triple
3 cells with candidates for 3 digits.
Naked Quad
4 cells with candidates for 4 digits.
Hidden Pair
2 digits with candidates in 2 cells.
Hidden Triple
3 digits with candidates in 3 cells.
Hidden Quad
4 digits with candidates in 4 cells. ]]> https://www.sudoku9981.com/sudoku-solving/Subsets.asp Sun, 29 Apr 2007 21:22:08 +0800 https://www.sudoku9981.com/sudoku/2007/05/06/subsets Solving Sudoku Strategy - Wings XY-Wing
Three cells with pivot cell XY and two pincer cells XZ and YZ.
XYZ-Wing
Three cells with pivot cell XYZ and two pincer cells XZ and YZ.
WXYZ-Wing
Four cells with pivot cell WXYZ and three pincer cells WZ, XZ and YZ.
]]> https://www.sudoku9981.com/sudoku-solving/Wings.asp Sun, 29 Apr 2007 21:22:08 +0800 https://www.sudoku9981.com/sudoku/2007/05/06/wings Solving Sudoku Strategy - Single Digit Patterns Skyscraper
Two parallel strong links, weakly connected at the base.
2-String Kite
Two crossing strong links, weakly connected in a box.
Empty Rectangle
A single-digit technique that makes use of a box whose candidates for that digit are contained within the union of a boxrow and a boxcol.
]]> https://www.sudoku9981.com/sudoku-solving/Single-Digit-Patterns.asp Sun, 29 Apr 2007 21:22:08 +0800 https://www.sudoku9981.com/sudoku/2007/05/06/sdp Solving Sudoku Strategy - Uniqueness Uniqueness Test
A set of techniques that avoids the Unique Rectangle deadly pattern.
Bivalue Universal Grave
A set of techniques that avoids the Bivalue Universal Grave deadly pattern.
BUG Lite
A set of techniques that avoids the BUG Lite deadly pattern.
]]> https://www.sudoku9981.com/sudoku-solving/Uniqueness.asp Sun, 29 Apr 2007 21:22:08 +0800 https://www.sudoku9981.com/sudoku/2007/05/06/uniqueness Solving Sudoku Strategy - Almost Locked Sets An Almost Locked Set is a group of N cells in a single house with candidates for N+1 digits. In other words, it is one cell short from being a locked set.

The simplest ALS is a single cell with 2 candidates. In a standard Sudoku an ALS can have a maximum size of 8 cells with 9 digits.

It is not easy to spot a large ALS, but there are often a lot of these sets present in the grid. Bivalue cells are always easy to spot with pencilmarks.

ALS-XZ rule
2 Almost Locked Sets with restricted common digit X perform eliminations for common digit Z.
ALS-XY-Wing rule
3 Almost Locked Sets with 2 restricted common digits Y and Z perform eliminations for common digit X.
Death Blossom
A stem cell of N candidates pointing to N petals, each an Almost Locked Set.
]]> https://www.sudoku9981.com/sudoku-solving/ALS.asp Sun, 29 Apr 2007 21:22:08 +0800 https://www.sudoku9981.com/sudoku/2007/05/06/als