Characteristic sequence

In mathematics, the characteristic sequence of a given sequence S is the sequence of 1's and 0's which tells you how often the elements of 'S' are in some set.

Given two sets: $A\subset B$ and a sequence $\{s_{n}\}_{n}\subset B$ the characteristic sequence of $\{s_{n}\}_{n}$ with respect to the set A is $\{\chi _{A}(s_{n})\}_{n}$, where $\chi _{A}$ is the indicator function (or characteristic function) of A.