DroopRules

Built-in rules

Droop has several rule implementations, summarized below. Each rule is self-contained, in that all the "business logic" of the rule lives in the rule file itself; the Droop framework provides support and housekeeping. Consequently, changes to the framework do not change the logic of a rule, and a rule can be read, understood and audited as a single unit.

Rules

Droop rule implementations include generic, parameterized Meek and Weighted Inclusive Gregory Method (WIGM) rules as well as rules that conform to specific publicly defined specifications.

• meek-prf is an implementation of the PR Foundation's Reference Meek Rule.
• wigm-prf is an implementation of the PR Foundation's Reference WIGM Rule.
• meek is a generic implementation of Meek's method, with an option for the Warren variant.
• wigm is a generic implementation of the Weighted Inclusive Gregory Method.
• mpls is the Minneapolis STV rule, a WIGM variant optimized for hand counting.
• scotland is the Scottish STV rule, a WIGM variant.
• qpq is an implementation of the Quota Preferential by Quotient rule (not actually STV, but similar in that it uses ordinal ranking and satisfies the Droop proportionality criterion).

The generic rules can be used for ad hoc implementations (or approximations) of other rules by creating simple command-line scripts. Droop includes two such scripts.

• oscar approximates the STV rule used for Oscar nominations
• irv uses the generic WIGM rule to count single-winner (IRV/AV) elections