Group strategy‐proof social choice functions with binary ranges and arbitrary domains: characterization results

We define different concepts of group strategy‐proofness for social choice functions. We discuss the connections between the defined concepts under different assumptions on their domains of definition. We characterize the social choice functions that satisfy each one of them and whose ranges consist of two alternatives, in terms of two types of basic properties. Finally, we obtain the functional form of all rules satisfying our strongest version of group strategy‐proofness.