A Complexity-of-Strategic-Behavior Comparison between Schulze's Rule and Ranked Pairs

Schulze's rule and ranked pairs are two Condorcet methods that both satisfy many natural axiomatic properties. is used in the elections of organizations, including Wikimedia Foundation, Pirate Party Sweden Germany, Debian project, Gento Project. Both rules immune to control by cloning alternatives, but little otherwise known about their strategic robustness, resistance manipulation one or more voters, adding deleting votes, bribery. Considering computational barriers, we show these types behavior NP-hard for (both constructive, making an alternative a winner, destructive, precluding from being winner). rule, comparison, remains vulnerable at least constructive single voter destructive coalition. As first such polynomial-time resist all manipulations, considering also broad support, seems worthwhile consider practical applications.