Definition:Iverson's Convention

Iverson's Convention is a notation which allows a compact means of assigning a value of $$1$$ or $$0$$ to a proposition $$P$$, depending on whether $$P$$ is true or false:


 * $$\left[{P}\right] = \begin{cases}

1 & : P \text { is true} \\ 0 & : P \text { is false} \end{cases}$$

It is sometimes seen specified as:
 * $$\left[{P}\right] = \begin{cases}

1 & : P \text { is true} \\ 0 & : P \text { otherwise} \end{cases}$$

... which can be useful in fields of mathematics where the Law of the Excluded Middle does not apply.

It is also known as the Iverson bracket notation.

The specific use of square brackets was advocated by Donald Knuth to avoid ambiguity in parenthesized logical expressions.