Consider a propagator for the constraint
2 . X = Yover a constraint store
Under domain propagation, the propagator can narrow the domains to
Under interval propagation, the propagator can narrow only the domain bounds, which yields
In practice, interval propagation is usually preferable over domain propagation because of its lower computational costs. But domain propagation often leads to considerably smaller search trees (figure 2). In Alice, some propagators have an additional argument conlevel. There you can specify the propagators consistency level.