Monotone Strategyproofness

• BSE Working Paper: 110197 | September 15
• Keywords: strategyproofness , Kemeny sets , misrepresentations , dominant strategy
• JEL codes: C72, D41
• strategyproofness
• Kemeny sets
• misrepresentations
• dominant strategy

We propose a way to compare the extent of preference misrepresentation between two strategies. We define a mechanism to be monotone strategyproof when declaring a “more truthful” preference ordering in the mechanism dominates – with respect to the true preferences – declaring a less truthful preference ordering. Our main result states that a mechanism is strategyproof if, and only if, it is monotone strategyproof. This result holds for any deterministic social choice function on any domain; for probabilistic social choice functions it holds under a mild assumption on the domain.