Iverson bracket

Named after Kenneth E. Iverson, who introduced this notation in his programming language APL.

Iverson bracket (plural Iverson brackets)

1. (mathematics) A notation that denotes a number that is 1 if the condition in square brackets is satisfied, and 0 otherwise, i.e. (where P is a true or false statement)

   ${\displaystyle [P]={\begin{cases}1&{\text{if }}P{\text{ is true;}}\\0&{\text{otherwise.}}\end{cases}}}$