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3.7 KiB

Majority Judgment Library for Java

MIT Build Status Release Join the Discord chat at

Test-driven java library to help deliberate using Majority Judgment.

The goal is to be scalable, reliable, fast and extensible. We therefore use a score-based algorithm and no floating-point arithmetic whatsoever.

Example Usage

Collect the tallies for each Proposal (aka. Candidate) by your own means, provide them to the MajorityJudgmentDeliberator, and get back the rank of each Proposal.

Let's say you have the following tally:

To Reject Poor Passable Somewhat Good Good Very Good Excellent
Proposal A 4 5 2 1 3 1 2
Proposal B 3 6 2 2 2 1 2
DeliberatorInterface mj = new MajorityJudgmentDeliberator();
TallyInterface tally = new Tally(new ProposalTallyInterface[] {
        // Amounts of judgments received for each grade, from "worst" grade to "best" grade
        new ProposalTally(new Integer[]{4, 5, 2, 1, 3, 1, 2}),  // Proposal A
        new ProposalTally(new Integer[]{3, 6, 2, 1, 3, 1, 2}),  // Proposal B
        // …
}, 18);
ResultInterface result = mj.deliberate(tally);

// Each proposal result has a rank, and results are returned by input order
assert(2 == result.getProposalResults().length);
assert(2 == result.getProposalResults()[0].getRank());  // Proposal A
assert(1 == result.getProposalResults()[1].getRank());  // Proposal B

Got more than 2³² judges? Use a Long[] in a ProposalTally.

Got even more than that ? Use BigIntegers !

Want to set a static default grade ? Use a TallyWithDefaultGrade instead of a Tally.


  • Unit-Tests
  • Deliberation algorithm
    • Tally Analysis
    • Score Calculus
    • Ranking
  • Release v0.1.0
  • Guess the amount of judges
  • Allow defining a default grade
    • Static Grade (configurable)
    • Median Grade
    • Normalization (using least common multiple)
  • Release v0.2.0
  • Publish on package repositories
    • Gradle
    • Maven
    • … ? (please share your knowledge to help us!)
  • Release v0.3.0
  • Use it somewhere in another app, adjust API as needed (one last time)
  • Release v1.0.0

Gondor calls for Help!

We are not accustomed to Java library development and we'd love reviews from seasoned veterans !

Feel free to fork and request merges for your contributions and active readings !

Run the test-suite

Install maven, and run:

mvn test

Maven is available as a debian package: apt install maven

You can also use a runner in Eclipse. (CTRL+F11 to rerun)


MITDo whatever you want except complain.

Majority Judgment itself is part of the Commons, obviously.

Fund us

We'd love to invest more energy in Majority Judgment development.

Please consider funding us, every bit helps :