Latest Changes and Additions

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

Forcing Nets
Date Created: Monday 9-Mar-2026
Last Updated: Friday 27-Mar-2026
Explanation of Forcing Nets - an expansion of Forcing Chains using Alternating Inference Chains.

What's New
Date Created: Monday 17-Aug-2009
Last Updated: Friday 13-Mar-2026


BUG
Date Created: Friday 11-Apr-2008
Last Updated: Monday 9-Mar-2026
Sudoku Strategy. BUG stands for Bi-Value Universal Grave. It is a formation that relies on the uniqueness of the solution and an array of bi-value cells.

Cell Forcing Chains
Date Created: Saturday 6-Mar-2010
Last Updated: Monday 2-Mar-2026
Sudoku Strategy. This is a Forcing Chains Strategy. It finds eliminations by comparing the results of two chains starting with a bi-value cell assuming either candidate in the cell is turned on.

Death Blossom
Date Created: Friday 11-Apr-2008
Last Updated: Monday 2-Mar-2026
Sudoku Strategy. Death Blossom is based on extending Aligned Pair Exclusion but uses Almost Locked Sets to make some clever reductions. It is complex.

Avoidable Rectangles
Date Created: Sunday 13-Apr-2008
Last Updated: Sunday 1-Mar-2026
Sudoku Strategy. Avoidable Rectangles is a strategy which, uniquely among all strategies, relies on clues and solved cells rather than potential candidates.

Various Static Patterns
Date Created: Wednesday 14-May-2025
Last Updated: Sunday 1-Mar-2026


X-Cycles
Date Created: Saturday 12-Apr-2008
Last Updated: Wednesday 25-Feb-2026
Sudoku Strategy. 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.

X-Cycles (Part 2)
Date Created: Sunday 4-May-2008
Last Updated: Wednesday 25-Feb-2026
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.

Daily Jigsaw Sudoku
Date Created: Thursday 8-Sep-2011
Last Updated: Wednesday 18-Feb-2026
The Daily Jigsaw Sudoku puzzle by Andrew Stuart. This Jigsaw Sudoku can be completed directly on the web page - just enter numbers in the cells. Have fun!