# Alldifferent constraint

is a global constraint that is imposed on $LaTeX: n$ variables, $LaTeX: x_1, \dots, x_n$, stating that every variable is assigned a different value.
In other words, it represents the set of disequalities $LaTeX: x_1 \neq x_2, x_1 \neq x_3, \dots, x_{n-1} \neq x_n$, however, typically, algorithms for all-different propagate far more efficiently than the set of disequality constraints.