June 2018 Project: Judgment Aggregation

This is the website for the June 2018 Master of Logic project on Judgment Aggregation. We will post all information related to the project on this page.
This project is based on the Computational Social Choice course given by Ulle Endriss in 2015.


The Handbook of Computational Social Choice is a great resource for further reading on the topics covered in the project and many more. Trends in Computational Social Choice is also a good reference for what's going on with more current research (chapter 7 is about belief merging and JA, and chapter 8 is about complexity & strategic behavior in JA. Chapter 9 is about social networks and there are parts that are relevant to JA).


We'll have four homeworks, one for each lecture in the first week. These should not take up too much time, and are mostly a way for you (and us) to check if you've understood the material. They are due the day after we post them, at 11am. You can email them to us or bring a paper copy to the lecture.


Your presentations in the second week should be similar to the format of the lectures of the first week. Each presentation should be around one hour including questions. The purpose is for each of you to present your paper in such a way that everyone in the audience leaves with a basic understanding of what the paper is about, and the main results. You will be the only one in the room who has read the paper, so when in doubt, go slow. Don't be afraid to make things interactive (we'd love to see some stars in the slides)!

Here is some advice on giving a talk by Ulle Endriss. Most things you need to consider before giving any kind of presentation are mentioned, so it's helpful to read even if you might not end up implementing all his suggestions. Note that some of it is written with conference-style talks in mind, so you can ignore those parts, or save them somewhere in the back of your mind for future endeavors.

When you are in the audience, ask questions! Even if you think they might be stupid (this doubles as a charitable act: you'll help out the person with the same question who is too concerned with looking smart to ask). These presentations are a prime opportunity to get used to interrupting lectures in a friendly environment, and for the presenters to get used to being interrupted. Note that it is obligatory to attend all these presentations.

Here is a simple beamer template for those of you who might want it to make your slides. Feel free to use/create your own or play around with this one to make it more your own style.


In the third week you should all have chosen a paper topic and have started working on your idea. During this week we want to set up meetings with each of you to discuss (and approve) your idea and discuss what you'll focus on going forward. By the end of the second week you should have already thought a bit about a potential topic and have scheduled a meeting with us for either Monday (18th) or Tuesday (19th).

What we Expect from your Paper: You have two options for the final paper. You can either come up with an original idea and develop it as far as you can, or you can do a thorough analysis of existing work (note that this does not mean summarising a few papers, your insights should still be original even though you do not prove new results). We highly encourage you to go with the first option, even if you only have the seed of an idea. Since this is a short project, it is ok if you don't manage to prove some amazing result, as long as you explain what your goal was and why you did not manage to come up with a proof (this does not mean something like "it was hard and I didn't have much time"). We expect everything in your papers to be correct, and well written.

The deadline for the paper is at the end of the fourth week, but you will need considerable time for the pre-writing work that goes into the paper so get started early.

In principle, any paper topic related to JA is fair game. If anything piqued your interest during the first couple weeks and you already have a vague idea, that's great! Come talk to us and we'll help you make it less vague.

For those of you who aren't sure what to write about, we have a few suggestions for possible topics below (of course, you can also find inspiration in the list of papers we posted for the presentations):

When you get to the writing stage, Ulle has you covered once again with some advice on writing a paper.

Your paper should be around 4-5 pages long (including references), using the IJCAI LaTeX style. The submission deadline for the paper is Friday 29 June 2018.

Week 1


Monday June 4th, 11-13Introduction to Computational Social Choice in general and Formal Framework of JA (slides), (homework 1).
Notes: I've changed the slides to correct the example for the Discursive Dilemma (thanks Dimitris!). I've also added a more intuitive explanation for why we sometimes might want the Neutrality axiom to be violated.
Tuesday June 5th, 11-13Ways out of List & Pettit impossibility and axiomatic characterisation of (classes of) rules (slides), (homework 2). Notes: I've added a reference to the paper which has the result about complexity of Kemeny. Note that it is one of the papers available for presentation.
Wednesday June 6th, 11-13How the structure of the agenda relates to consistency of rules. Agenda characterisations (slides part a, slides part b), (homework 3).Notes: I will do a sketch of the lemma we used for the hw solution in lecture tomorrow. I suggest that you have a look at the proof from the second part of the lecture, it is worth it!
Thursday June 7th, 11-13Stratetic behavior in JA, and a bit of truth tracking. Notes: Remember to let us know by the end of today which paper you'd like to present! We've put up a simple template for beamer slides in the presentation section above. (slides part a, slides part b), (homework 4).

Week 2

Student presentations. Note that it is obligatory to attend all the presentations.

Monday June 11thWe'll take Monday off and do two presentations per day T-W-Th.
Tuesday June 12th, 11-13Federico talked about Binary Aggregation-an alternate framework for JA, and Dimitris gave a presentation on the diffusion of binary opinions on a network, which employs the framework of Binary Aggregation!
Wednesday June 13th, 11-13Sven talked about agenda manipulation (a different kind of strategic consideration), and Rachael presented some complexity results in JA.
Thursday June 14th, 11-13Kristoffer talked about some JA rules as truth-trackers, and May talked about the framework of Belief Merging.

COMSOC Seminar, Monday June 11: Michael Morreau (Tromsø), Give me your biased, your unschooled, your ignorant masses, ....

Week 3

Meetings to discuss paper progress.

Monday June 18th 11:00-11:20Rachael
Monday June 18th 11:30-11:50Sven
Monday June 18th 12:00-12:20May
Tuesday June 19th 11:00-11:20Federico
Tuesday June 19th 11:30-11:50Dimitris
Tuesday June 19th 12:00-12:20Kristoffer

Special Event: Dutch Social Choice Colloquium on Friday June 22.

Week 4

Advice on writing a paper by Ulle Endriss.

Possible papers for presentation:

Reserved papers have your name at the end.

Alternative Inputs and Outputs Complexity of JA Logics and JA JA on "Networks" Strategic Behavior Truth Tracking Related Frameworks