### 3.7.42. Channelling constraint

Constraints that allow for linking two models of the same problem. Usually channelling constraints show up in the following context:

• When a problem can be modelled by using different types of variables (e.g., 0 -1 variables, domain variables, set variables),

• When a problem can be modelled by using two distinct matrices of variables representing the same information redundantly,

• When, in a problem, the roles of the variables and the values can be interchanged. This is typically the case when we have a bijection between a set of variables and the values they can take.

• When, in a problem, we use two time coordinates systems (e.g., see $\mathrm{𝚌𝚊𝚕𝚎𝚗𝚍𝚊𝚛}$).