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Hidden Quad

A Hidden Quad is a Hidden Subset of size 4.

When all candidates for 4 digits in a house are limited to only 4 cells, these cells must contain these 4 digits. Subsequently, all remaining candidates can be removed from these 4 cells.


The following example shows a Hidden Quad in the 6th box.


This page was last modified 19:03, 22 January 2007.