SI 683 Reputation Systems

Instructor: Rahul Sami

1.5 Credit, 7-week course module
Second half of Winter 2009
Tuesday, Thursday 10:30am-12:00noon, 409WH
Office hours: Tue 1:30-2:30pm 417B West Hall; Wed 4:30-5:30pm 3246E SI-N

Course Learning Objectives:

In this course, you will learn about the design of reputation systems: design choices, benefits, threats, and limitations. At the end of this course, a student should be able to critically analyze a reputation system design to identify strengths and potential weaknesses, and to design a reputation system for a particular domain with a clear idea of the tradeoffs involved.

Academic Integrity Policy

The UM and SI Academic Integrity Policy applies to this course: Collaboration while working on homework problems, and while discussing and interpreting the reading assignments, is encouraged. Active learning is effective. Collaboration will be especially valuable in summarizing the reading materials and picking out the key concepts. You must, however, write your homework submission on your own, in your own words, before turning it in. If you worked with someone on the homework before writing it, you must list any and all collaborators on your written submission.

All written submissions must be your own, original work. Original work for narrative questions is not mere paraphrasing of someone else's completed answer: you must not share written answers with each other at all. At most, you should be working from notes you took while participating in a study session. Largelyduplicate copies of the same assignment will receive an equal division of the total point score from the one piece of work. You may incorporate selected excerpts from publications by other authors, but they must be clearly marked as quotations and must be attributed. If you build on the ideas of prior authors, you must cite their work. You may obtain copy editing assistance, and you may discuss your ideas with others, but all substantive writing and ideas must be your own, or be explicitly attributed to another. See the Rackham Graduate policy on Academic and Professional Integrity for the definition of plagiarism, and associated consequences.

Accommodations for Students with Disabilities

If you think you need an accommodation for a disability, please let me know at your earliest convenience. Some aspects of this course, the assignments, the in-class activities, and the way we teach may be modified to facilitate your participation and progress. As soon as you make me aware of your needs, we can work with the Office of Services for Students with Disabilities (SSD) to help us determine appropriate accommodations. SSD (734-763-3000; http://www.umich.edu/~sswd) typically rec- ommends accommodations through a Verified Individualized Services and Accommodations (VISA) form. I will treat any information you provide as private and confidential.

Overview:

The Internet enables interactions, commercial and non-commercial, between people across geographical and social boundaries. Ideally, these interactions are mutually beneficial, but they may also be exploitative or fraudulent. For example, buying an item on an online auction may get you a bargain, but you may also lose money if the other party ships you poor-quality goods, or does not send anything at all. Ideally, you would like to engage in interactions with reliable and trustworthy entities, but this is often difficult for two reasons: (1) You may not have information about the quality of the other party, or the value of the exchange; (2) The other party may have incentives that conflict with your own, and may thus seek to manipulate the interaction to your detriment.

Reputation systems are widely used to address these problems in online forums; for example, eBay.com, Amazon.com, and Yahoo.com all use reputation systems in their auctions. A user's reputation is an aggregate of feedback from all her past trading partners. Ideally, it will reveal information about the average quality of those transactions; further, the desire to maintain a high reputation gives her an incentive to honestly execute the current transaction. However, a reputation system needs to be designed carefully, and tailored to its application setting: poorly designed reputation systems may be uninformative or prone to manipulation.

In this course, we will study the design and critical analysis of reputation systems. We will discuss incentive issues involved in motivating users to behave honestly and to give honest feedback, as well as other practical aspects of designing a reputation system, such as the format of feedback input and retrieval. We will also study ways in which strategic parties may try to circumvent the system, and techniques to defend against these attacks.

Prerequisites

Course Schedule

Course Work and Assessment