A parametric propagator for pairs of Sum constraints with a discrete convexity property

We introduce a propagator for pairs of Sum constraints, where the expressions in the sums respect a form of convexity. This propagator is parametric and can be instantiated for various concrete pairs, including Deviation, Spread, and the conjunction of Linear≤ and Among. We show that despite its generality, our propagator is competitive in theory and practice with state-of-the-art propagators.