# Element constraint

is a global constraint that is true iff a variable $LaTeX: z$ is the $LaTeX: y$th element of an array $LaTeX: X$. More specifically, it involves a 1-dimensional variable array $LaTeX: X = \langle x_1, \dots, x_n \rangle$, an integer variable $LaTeX: y$ and variable $LaTeX: z$, where $LaTeX: X[y] = z$, typically written as "element(X,y,z)".