Maskin monotonicity

{{Technical|date=February 2024}}

Maskin monotonicity is a desired property of voting systems suggested by Eric Maskin.{{cite journal|doi=10.1111/1467-937X.00076|title=Nash Equilibrium and Welfare Optimality|journal=Review of Economic Studies|volume=66|pages=23–38|year=1999|last1=Maskin|first1=Eric|citeseerx=10.1.1.122.2734|s2cid=16282419 }}

Each voter reports his entire preference relation over the set of alternatives. The set of reports is called a preference profile. A social choice rule maps the preference profile to the selected alternative.

For a preference profile P_1 with a chosen alternative A_1, there is another preference profile P_2 such that the position of A_1 relative to each of the other alternatives either improves or stays the same as in P_1. With Maskin monotonicity, A_1 should still be chosen at P_2.{{cite journal|doi=10.1007/s00355-014-0835-6|title=Maskin-monotonic scoring rules|journal=Social Choice and Welfare|volume=44|issue=2|pages=423|year=2014|last1=Doğan|first1=Battal|last2=Koray|first2=Semih|url=http://repository.bilkent.edu.tr/bitstream/11693/12509/1/7936.pdf|hdl=11693/12509|s2cid=253844286 |hdl-access=free}}

Maskin monotonicity is a necessary condition for implementability in Nash equilibrium. Moreover, any social choice rule that satisfies Maskin monotonicity and another property called "no veto power" can be implemented in Nash equilibrium form if there are three or more voters.

See also

References