In this paper, we design the optimal contract when two agents can collude under asymmetric information. They have correlated types, produce complementary inputs and are protected by limited liability. Therefore, a joint manipulation of reports allows them to internalize informational and...

The paper starts with the wide variability of nonpoint water nitrogenous pollution generated by agriculture. This variability depends especially on climate, soil types and farming systems. Our interdisciplinary researches, mainly based on two sites in France, show that space and time...