# Verity

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A **verity** is a statement which is true for all alternatives in a limited set.

Suppose we have a cell **A** and as cell **B**. Consider the following implication chains:

A=1 => ... => B=2 A<>1 => ... => B=2

Cell **A** can either contain digit 1 or it does not. There is no middle ground. When both situations lead to the placement of digit 2 in cell **B**, this cell must contain digit 2. This is a verity.

The alternative term **veracity** is sometimes used for similar purposes, but there is no real distinction between these two terms.

The following situation shows how a verity can also be proven when there are more than 2 alternatives:

A=(1,2,3) A=1 => ... => B=2 A=2 => ... => B=2 A=3 => ... => B=2

In this sample, cell **A** has candidates for digits 1,2 and 3. Each of these force digit 2 in cell **B**.