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

Main Page
Date Created: Thursday 10-Apr-2008
Last Updated: Saturday 16-May-2015
Strategies for Sudoku, Sudoku X, Killer Sudoku and Jigsaw Sudoku - and the home of logical puzzle maker Andrew Stuart

Single's Chains
Date Created: Saturday 29-Jan-2011
Last Updated: Saturday 25-Apr-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.

Finned X-Wing
Date Created: Saturday 12-Apr-2008
Last Updated: Sunday 29-Mar-2015
Sudoku Strategy. Finned X-Wing extend X-Wings but it has extra candidates of X that prevent one of the two pairs normally required. Eliminations are still possible in this fin.

Unit Forcing Chains
Date Created: Saturday 6-Mar-2010
Last Updated: Sunday 29-Mar-2015
Sudoku Strategy. This is a Forcing Chains Strategy. It finds eliminations by comparing the results of chains starting with all candidates N in a unit and assuming any of them are turned on.

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.

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.

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.