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A quick list of the latest updates and additions to this site:

3D Medusa
Date Created: Saturday 6-Mar-2010
Last Updated: Sunday 15-Feb-2015
Sudoku Strategy. 3D Medusa takes chain building into all the dimensions of the Sudoku board. That is, by making links among rows, columns and boxes - and in bi-value cells. Many types of eliminations are possible with this network approach.

Single's Chains
Date Created: Saturday 29-Jan-2011
Last Updated: Sunday 15-Feb-2015
Sudoku Strategy. Single's Chains, also known as Simple Colouring is a chaining strategy and part of a large family of such strategies. Cells and units with only two remaining candidates N are used to make links and find contradictions.

What's New
Date Created: Monday 17-Aug-2009
Last Updated: Sunday 15-Feb-2015

Alternating Inference Chains
Date Created: Saturday 12-Apr-2008
Last Updated: Sunday 18-Jan-2015
Sudoku Strategy.Alternating Inference Chains are explained. This is the fundamental chaining strategy used to find eliminations on cells that can see the start and end of a chain.

XY-Chains
Date Created: Friday 11-Apr-2008
Last Updated: Saturday 27-Dec-2014
Sudoku Strategy. XY-Chains are the work-horse of chaining strategies and are very easy to use when the board contains many bi-value cells. When the start and end cells can see a common candidate eliminations can be made.

X-Cycles (Part 2)
Date Created: Sunday 4-May-2008
Last Updated: Saturday 27-Dec-2014
Sudoku Strategy continued. X-Cycles are simple chaining strategies that stick to candidate N. They are Alternating Inference Chains based on following the consequences of turning candidates on and off.

Sword-Fish Strategy
Date Created: Friday 11-Apr-2008
Last Updated: Saturday 27-Dec-2014
Sudoku Strategy. Sword-Fish extends X-Wings into three rows and three columns. Candidate eliminations are possible where the cells that form the Sword-Fish are the only possible places for a solution on candidate N.

X-Wing Strategy
Date Created: Thursday 10-Apr-2008
Last Updated: Saturday 27-Dec-2014
Sudoku Strategy. X-Wings are the simplest of the chaining formations and are very easy to spot. They use four cells in a rectangle to make eliminations in the row or column.

XYZ-Wing
Date Created: Friday 11-Apr-2008
Last Updated: Saturday 27-Dec-2014
Sudoku Strategy. XYZ-Wings extend Y-Wings to three numbers and are three cell formations used to eliminate candidate elsewhere. They use a common candidate method to find contradictions.

Y-Wing Strategy
Date Created: Friday 11-Apr-2008
Last Updated: Saturday 27-Dec-2014
Sudoku Strategy. Y-Wings are simple three cell formations used to eliminate a candidate in a fourth cell. They are also the shortest versions of certain types of Alternating Inference Chains.