Iverson bracket

== English == === Etymology === Named after Kenneth E. Iverson, who introduced this notation in his programming language APL. === Noun === Iverson bracket (plural Iverson brackets) (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) [ P ] = { 1 if P is true; 0 otherwise. {\displaystyle [P]={\begin{cases}1&{\text{if }}P{\text{ is true;}}\\0&{\text{otherwise.}}\end{cases}}}