Having built chains with cells and units we now move onto two further building blocks. 'Groups' are a step up from what we have been employing so far but this example should make them appear relatively simple.

The example is an X-Cycle on 3 starting and ending in B1.

A group is a set of two or three cells aligned on a row or column - and in the same box - which we can consider as a single cell for the purposes of our chain. Because they are aligned it a chain coming to them on the alignment doesn't need to care which, if any, are the solutions. In the example we are starting at B1 and going counter-clockwise - to G1 and then to G5. From G5 we can see the of 3s in [A5,B5,C5]. The alignment is critical. This won't be possible, in this example, coming from any other direction.