Iverson bracket

参考    Iverson bracket - 云+社区 - 腾讯云

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]={\begin{cases}1&{\text{if }}P{\text{ is true;}}\\0&{\text{otherwise.}}\end{cases}}}" role="presentation" style="position: relative;">[P]={\begin{cases}1&{\text{if }}P{\text{ is true;}}\\0&{\text{otherwise.}}\end{cases}}}$\text{[P]={begin{cases}1\&{text{if }}P{text{ is true;}}0\&{text{otherwise.}}end{cases}}}}$