If we assume that {0}, it follows, through an XY Forcing Chain, that {1}. Therefore we can conclude that {2}.
Unary Chains start with a simple assumption that a cell is/not one of its potential values, which is proven to be either true or false.
X-Chaining means that:
(1) when a cell is assumed to be a value
then other possible positions for this value in this cells three region
must be removed
(2) when a cell is assumed to NOT be one of its potential values
and there are only two positions for this value in one (or more) of this
cells three regions
then the other cell(s) must be this value.
Y-Chaining means that:
(1) when a cell is assumed to be a value
then all the other potential values of this cell must be removed
{2) when a cells is assumed to NOT be one of its potential values
and there are only two potential values for this cell
then this cell must be the other value.
The Forcing Chain consists of a chain of implications based on simple rules. The details of the Forcing Chain are given below.
Details of the Forcing Chain:
{3}