The paper extends the factor and decomposition theorems for functions to the category Rel of sets and relations. The converse theorems are also stated and proved. We show that the (retraction, isomorphism, section)-decomposable relations form a closure system on Mor (Rel), and characterize it in...

This paper is concerned with the procedural aspects of collective choice and the impact of the parties' participation rights on the optimal mechanism. We find that the mechanism designer generally benefits from the selective engagement of the agents-the exclusion of some agent-types from the...