Minimal Defense criterion
The Minimal Defense criterion for voting systems is similar to and was inspired by the Strong Defensive Strategy criterion.
Statement of Criterion
Steve Eppley gives this official definition:
"If more than half of the voters prefer alternative y over alternative x, then that majority must have some way of voting that ensures x will not be elected and does not require any of them to rank y equal to or over any alternatives preferred over y."
This definition is most similar to that of SDSC. Another definition suggested by Eppley makes reference only to the cast votes:
If more than half of the voters rank Y above X, and X above no other candidate, then X must not be elected.
It's also required that the method permits voters to submit complete or incomplete rankings. In particular, truncation must be an option: It's not adequate for the method to require that the voters rank X strictly below every other candidate.
Complying Methods
Methods satisfying Minimal Defense include Steve Eppley's own Maximize Affirmed Majorities method, Cloneproof Schwartz Sequential Dropping using winning votes as the measure of defeat strength, Jobst Heitzig's River method, and methods electing from the CDTT set.