Sunday, February 22, 2015

STOC 2015 Call for Workshops and Tutorials

Sanjeev Khanna and Chandra Chekuri are co-chairing the STOC 2015 workshops and tutorials, and are looking for submissions. The call is below:

Call for STOC 2015 Workshop and Tutorial Proposals

  • Workshop and Tutorial Day: Sunday, June 14, 2015
  • Workshop and Tutorial Co-Chairs: Chandra Chekuri and Sanjeev Khanna
  • Submission deadline: March 20, 2015
  • Notification: March 30, 2015
On Sunday, June 14, immediately preceding the main conference, STOC 2015 will hold a workshop-and-tutorials day. We invite groups of interested researchers to submit workshop or tutorial proposals. The goal of a workshop is to provide an informal forum for researchers to discuss important research questions, directions, and challenges. Connections between theoretical computer science and other areas, topics that are not well represented at STOC, and open problems are encouraged as workshop topics. Organizers are completely free to choose their workshop formats (invited speakers, panel discussions, etc.). The program for June 14th may also involve tutorials, each consisting of 1-2 survey talks on a particular area, and we welcome tutorial proposals as well.
STOC does not have funds to pay travel expenses or honoraria to invited workshop and tutorial speakers. Workshop and tutorials attendance will be free, and there is no separate registration for attending them. STOC will support coffee breaks for the workshops/tutorials attendees but no lunch will be provided. Note that STOC registration neither includes FCRC registration for Sunday, June 14 nor covers lunch for Sunday, June 14. Workshop/tutorial attendees who wish to attend another FCRC conference on June 14, would need to register for that conference.

Proposal submission

Workshop and tutorial proposals should be no longer than 2 pages. Please include a list of names and email addresses of the organizers, a description of the topic and the goals of the workshop or tutorial, the proposed workshop format (invited talks, contributed talks, panel, etc.), and proposed or tentatively confirmed speakers if known. Please also indicate the preferred length of time for your workshop or tutorial, along with the minimum acceptable time. We anticipate a 4-5 hour block for each workshop and a 2-4 hour block for each tutorial. Please feel free to contact the Workshop and Tutorial Co-Chairs at the email addresses below if you have questions about workshop or tutorial proposals.

Submission deadline

Proposals should be submitted by March 20, 2015, via email to chekuri@illinois.edu and sanjeev@cis.upenn.edu. Proposers will be notified by March 30, 2015, about whether their proposals have been accepted.

http://acm-stoc.org/stoc2015/callforworkshops.html

Friday, February 13, 2015

Bringing Differential Privacy to the Masses <3

This Valentines Day, we'll be bringing differential privacy to the (scientific) masses, with a session at the AAAS annual meeting in San Jose.

If you happen to be attending, you should stop by: https://aaas.confex.com/aaas/2015/webprogram/Session9556.html

Wednesday, January 28, 2015

NetEcon 2015

Patrick Loiseau, Adam Wierman, and I are co-chairing the 2015 NetEcon workshop, to be held in conjunction with EC and Sigmetrics at this year's FCRC in Portland. You should stop by if you are attending any of the FCRC conferences, (and submit a paper). If you haven't been to a previous iteration, this workshop brings together people interested in game theory from both the networking and theory/AI communities, so is a great place to present work that might be of interest to both communities, or to pick up problems that are interesting from a different community than yours.

We've got a great set of invited speakers: R. Srikant, Ricky Vohra, and Eva Tardos.

So start thinking about what you want to submit -- you've only got about 3 months.
*******************************************************************
Call For Papers:

         NetEcon 2015: The 10th Workshop on the Economics of Networks, 
Systems and Computation
         At FCRC 2015, in conjunction with ACM EC and ACM SIGMETRICS
         Monday, June 15, 2015 (Portland, Oregon, USA)

http://netecon.eurecom.fr/NetEcon2015/


*******************************************************************
INVITED SPEAKERS

     * *R. Srikant*, University of Illinois at Urbana-Champaign
     * *Rakesh V. Vohra*, University of Pennsylvania
     * *Eva Tardos*, Cornell University


*******************************************************************
CALL FOR PAPERS

Today's communication networks and networked systems are highly complex 
and heterogeneous, and are often owned by multiple profit-making 
entities. For new technologies or infrastructure designs to be adopted, 
they must not be only based on sound engineering performance 
considerations but also present the right economic incentives. Recent 
changes in regulations of the telecommunication industry make such 
economic considerations even more urgent. For instance, concerns such as 
network neutrality have a significant impact on the evolution of 
communication networks.

At the same time, communication networks and networked systems support 
increasing economic activity based on applications and services such as 
cloud computing, social networks, and peer-to-peer networks. These 
applications pose new challenges such as the development of good pricing 
and incentive mechanisms to promote effective system-wide behavior. In 
relation to these applications, security and privacy also require 
consideration of economic aspects to be fully understood.

The aim of NetEcon is to foster discussions on the application of 
economic and game-theoretic models and principles to address challenges 
in the development of networks and network-based applications and 
services. NetEcon was established in 2006 (succeeding to the P2PECON, 
IBC and PINS workshops) and merged with the W-PIN workshop in 2013. We 
invite submission of extended abstracts describing original research on 
theoretical/methodological contributions or on applications to cases of 
interest. It is our hope that NetEcon will serve as a feeder workshop, 
i.e., that expanded, polished versions of extended abstracts will appear 
later in major conference proceedings and refereed journals of relevant 
research communities.

Topics of interest include (but are not limited to):

     * Pricing of resources in communication networks, grids, and cloud 
computing
     * Pricing of information goods and services; copyright issues, 
effect of network externalities (e.g., in social network)
     * Economic issues in universal broadband access; economics of 
interconnection and peering
     * Effects of market structure and regulations (e.g., network 
neutrality)
     * Economics of network security and privacy; valuation of personal data
     * Auctions with applications to networks: spectrum auctions, 
auction-based marketplaces for network and cloud resources
     * Incentive mechanisms for networks: peer-to-peer systems, clouds, 
wireless networks, spam prevention, security
     * Methods for engineering incentives and disincentives (e.g., 
reputation, trust, control, accountability, anonymity)
     * Empirical studies of strategic behavior (or the lack thereof) in 
existing, deployed systems
     * Design of incentive-aware network architectures and protocols
     * Game-theoretic models and techniques for network economics: large 
games, learning, mechanism design, interaction of game theory and 
information theory or queuing theory, information exchange, diffusion, 
dynamics of cooperation and network formation, trades in social and 
economic networks
     * Algorithmic mechanism design for network systems
     * Critiques of existing models and solution concepts, as well as 
proposals of better models and solution concepts
     * Studies of open collaboration, peer production, crowdsourcing, 
and human computation.


*******************************************************************
SUBMISSION FORMATTING GUIDELINES AND PROCEEDINGS

Submissions must be in the form of extended abstracts of 3-4 pages, 
including all figures, tables, references, appendices, etc. They must be 
formatted according to the standard alternate ACM PER double column 
format using letter paper. You are encouraged to use the ACM 
sig-alternate-per latex template 
(http://www.sigmetrics.org/sig-alternate-per.cls).

Accepted extended abstracts will be published in a special issue of ACM 
Performance Evaluation Review (PER) and will be available online through 
ACM portal digital library. Authors of accepted abstracts grant ACM 
permission to publish them in print and digital formats.

Note that authors retain the copyright of their work published in ACM 
PER, with freedom to submit it elsewhere. Yet, authors for whom 
publication of a 3-4 pages extended abstract in the NetEcon 2015 
proceedings would preclude later publication of an expanded version in 
the relevant venue may elect to contribute only a one-page abstract of 
their submitted extended abstract to the NetEcon 2015 proceedings. Such 
an abstract should include the URL of a working paper or preprint that 
contains the main results presented at the NetEcon workshop. Authors 
will make this decision after receiving a notice of acceptance.

If the number of excellent submissions is larger than we have space to 
allot presentations for, some authors will be offered the opportunity to 
present their work during a poster session.


*******************************************************************
COMMITTES

PC CHAIRS
     Patrick Loiseau (EURECOM, France)
     Aaron Roth (UPenn, USA)
     Adam Wierman (Caltech, USA)

WEBMASTER
     Michela Chessa (EURECOM, France)

TECHNICAL PROGRAM COMMITTEE
     Matthew Andrews (Alcatel-Lucent Bell Labs, USA)
     Itai Ashlagi (MIT, USA)
     Moshe Babaioff (Microsoft Research, Israel)
     Tamer BaÅŸar (University of Illinois, Urbana-Champaign, USA)
     Bobby Bhattarcharjee (University of Maryland, USA)
     Rainer Böhme (WWU Münster, Germany)
     Kostas Bimpikis (Stanford University, USA)
     Eilyan Bitar (Cornell University, USA)
     Augustin Chaintreau (Columbia University, USA)
     Michela Chessa (EURECOM, France)
     kc claffy (CAIDA / UC San Diego, USA)
     Costas Courcoubetis (SUTD, Singapore and AUEB, Greece)
     Amogh Dhamdhere (CAIDA / UC San Diego, USA)
     Constantine Dovrolis (GeorgiaTech, USA)
     Rachid Elazouzi (University of Avignon, France)
     Sergey Gorinsky (Institute IMDEA Networks, Spain)
     Jens Grossklags (The Pennsylvania State University, USA)
     Roch Guerin (Washington University in St. Louis, USA)
     Nidhi Hegde (Alcatel-Lucent Bell Labs, France)
     Ekram Hossain (University of Manitoba, Canada)
     Stratis Ioannidis (Yahoo! labs, USA)
     Krisnamurthy Iyer (Cornell University, USA)
     Rahul Jain (USC, USA)
     Ian Kash (Microsoft Research, UK)
     David Kempe (USC, USA)
     Peter Key (Microsoft Research, UK)
     Nikolaos Laoutaris (Telefonica Research, Spain)
     Dave Levin (University of Maryland, USA)
     Patrick Loiseau (EURECOM, France) -- co-chair
     Brendan Lucier (Microsoft Research, USA)
     John C. S. Lui (The Chinese University of Hong Kong, Hong Kong)
     Patrick Maillé (Institut Mines-Telecom / Telecom Bretagne, France)
     Jason Marden (University of Colorado, Boulder, USA)
     Ravi Mazumdar (University of Waterloo, Canada)
     Jeonghoon Mo (Yonsei University, South Korea)
     John Musacchio (UC Santa Cruz, USA)
     Andrew Odlyzko (University of Minnesota, Minneapolis, USA)
     Aaron Roth (UPenn, USA) -- co-chair
     Galina Schwartz (UC Berkeley, USA)
     Paul G. Spirakis (University of Liverpool, UK and CTI, Greece)
     Nicolás Stier Moses (Facebook Data Science, USA)
     Vijay Subramanian (University of Michigan, Ann Arbor, USA)
     John N. Tsitsiklis (MIT, USA)
     Bruno Tuffin (Inria, France)
     Adrian Vetta (McGill University, Canada)
     Steven Weber (Drexel University, USA)
     Adam Wierman (Caltech, USA) -- co-chair


*******************************************************************
IMPORTANT DATES

     * Wednesday April 22, 2015, 11:59pm PST: Submission deadline (firm)
     * Wednesday May 13, 2015: Notification to authors
     * Monday June 8, 2015: Final version for the workshop's website due
     * Monday June 15, 2015: Workshop in Portland
     * Monday July 13, 2015: Final version for the ACM PER proceedings due


*******************************************************************
ADDITIONAL INFORMATION

For more information, please contact the organizers or visit the 
workshop website: http://netecon.eurecom.fr/NetEcon2015/.

Tuesday, November 25, 2014

Differential Privacy Workshop in London

There will be a differential privacy workshop in London in April, accepting submissions soon. If you have something you are working on, consider submitting here. Some highlights:

-- Although the workshop will not have proceedings (so you can as usual submit a talk and still submit it to a conference of your choosing), exceptional submissions will be invited to a special issue of the Journal of Privacy and Confidentiality.

-- The PC is pretty inter-disciplinary. This is certainly not just a Theory-A workshop. Work on privacy in all areas is on topic.

-- You get to hear Jon Ullman give a (presumably excellent) talk. 


CALL FOR PAPERS
TPDP 2015
First workshop on the Theory and Practice of Differential Privacy
18th April 2015, London, UK
Affiliated to ETAPS
http://tpdp.computing.dundee.ac.uk

Differential privacy is a promising approach to the privacy-preserving
release of data: it offers a strong guaranteed bound on the increase
in harm that a user incurs as a result of participating in a
differentially private data analysis.

Researchers in differential privacy come from several area of computer
science as algorithms, programming languages, security, databases,
machine learning, as well as from several areas of statistics and data
analysis. The workshop is intended to be an occasion for researchers
from these different research areas to discuss the recent developments
in the theory and practice of differential privacy.

**Submissions**

The overall goal of TPDP is to stimulate the discussion on the
relevance of differentially private data analyses in practice. For
this reason, we seek contributions from different research areas of
computer science and statistics.

Authors are invited to submit a short abstract (4-5 pages maximum) of
their work by January 23, 2015. Abstracts must be written in English
and be submitted as a single PDF file at the EasyChair page for TPDP:
https://easychair.org/conferences/?conf=3Dtpdp2015

Submissions will be judged on originality, relevance, interest and
clarity. Submission should describe novel works or works that have
already appeared elsewhere but that can stimulate the discussion
between the different communities. Accepted abstracts will
be presented at the workshop.

The workshop will not have formal proceedings, but we plan to have a
special issue of the Journal of Privacy and Confidentiality devoted to
TPDP. Authors presenting valuable contributions at the workshop will
be invited to submit a journal version of their work right after the
workshop.


**Important Dates**

-January 23, 2015 - Abstract Submission
-February 10, 2015 - Notification
-February 14, 2015 - Deadline early registration ETAPS
-April 18, 2015 - Workshop

-May 15, 2015 Deadline for journal special issue


**Topics**

Specific topics of interest for the workshop include (but are not limited t=
o):
theory of differential privacy,
verification techniques for differential privacy,
programming languages for differential privacy,
models for differential privacy,
trade-offs between privacy protection and analytic utility,
differential privacy and surveys,
relaxations of the differential privacy definition,
differential privacy vs other privacy notions and methods,
differential privacy and accuracy,
practical differential privacy,
implementations for differential privacy,
differential privacy and security,
applications of differential privacy.


**Invited Speakers**

Jonathan Ullman - Simons Fellow at Columbia University,

Another invited speaker joint with HotSpot'15 to be confirmed.


**Program Committee**

Gilles Barthe - IMDEA Software
Konstantinos Chatzikokolakis - CNRS and LIX, Ecole Polytechnique
Kamalika Chaudhuri - UC San Diego
Graham Cormode - University of Warwick
George Danezis - University College London
Marco Gaboardi - University of Dundee
Matteo Maffei - CISPA, Saarland University
Catuscia Palamidessi - INRIA and LIX, Ecole Polytechnique
Benjamin C. Pierce - University of Pennsylvania
Aaron Roth - University of Pennsylvania
David Sands - Chalmers University of Technology
Chris Skinner - London School of Economics
Adam Smith - Pennsylvania State University
Carmela Troncoso - Gradiant
Salil Vadhan - Harvard University

Friday, August 15, 2014

Differential Privacy Book is Here

After a much longer time than either of us thought it would take, my book with Cynthia Dwork, "The Algorithmic Foundations of Differential Privacy" is finally available.

You have 3 options for obtaining a copy! (I must admit to not quite understanding the pricing model of our publisher).


  1. Hard Copy: You can buy a hard copy directly from NOW for $99 (http://www.nowpublishers.com/articles/foundations-and-trends-in-theoretical-computer-science/TCS-042/book-details) or from Amazon for $101 and free shipping (http://www.amazon.com/Algorithmic-Foundations-Differential-Privacy/dp/1601988184/ )
  2. "ebook" format (which I believe is just a downloadable pdf): If you don't have room on your book shelf, and are happy with a PDF, the book can be yours from NOW for only $240. This is a bargain -- coming in at 281 pages, this is less than 86 cents per digital "page".   (http://www.nowpublishers.com/articles/foundations-and-trends-in-theoretical-computer-science/TCS-042/book-details)
  3. Free download: The PDF is also available for free on my web page: http://www.cis.upenn.edu/~aaroth/privacybook.html

Friday, April 18, 2014

Lecture 12 -- Privacy Yields an Anti-Folk Theorem in Repeated Games

Last week, Kobbi Nissim gave us an excellent guest lecture on differential privacy and machine learning. The semester has gone by fast -- this week is our last lecture in the privacy and mechanism design class. (But stop by next week to hear the students present their research projects!)

Today we'll talk about infinitely repeated games. In an infinitely repeated game, n players repeatedly, in an infinite number of stages, play actions and obtain payoffs based on some commonly known stage game. Since the game is infinitely repeated, in order to make sense of players total payoff, we employ a discount factor delta that specifies how much less valuable a dollar is tomorrow compared to a dollar today. (delta is some number in [0, 1) ). In games of perfect monitoring, players perfectly observe what actions each of their opponents have played in past rounds, but in large n player games, it is much more natural to think about games of imperfect monitoring, in which agents see only some noisy signal of what their opponents have played.

For example, one natural signal players might observe in an anonymous game is a noisy histogram estimating what fraction of the population has played each type of action. (This is the kind of signal you might get if you see a random subsample of what people play -- for example, you have an estimate of how many people drove on each road on the way to work today by looking at traffic reports). Alternately, there may be some low dimensional signal (like the market price of some good) that everyone observes that is computed as a randomized function of everyone's actions today (e.g. how much of the good each person produced).

A common theme in repeated games of all sorts are folk theorems. Informally, these theorems state that in repeated games, we should expect a huge multiplicity of equilibria, well beyond the equilibria we would see in the corresponding one-shot stage game. This is because players observe each other's past behavior, and so can threaten each other to behave in prescribed ways or else face punishment. Whether or not a folk theorem is a positive result or a negative result depends on whether you want to design behavior, or predict behavior. If you are a mechanism designer, a folk theorem might be good news -- you can try and encourage equilibrium behavior that has higher welfare than any equilibrium of the stage game. However, if you want to predict behavior, it is bad news -- there are now generically a huge multiplicity of very different equilibria, and some of them have much worse welfare than any equilibrium of the stage game.

In this lecture (following a paper joint with Mallesh Pai and Jon Ullman) we argue that:

  1. In large games, many natural signaling structures produce signal distributions that are differentially private in the actions of the players, where the privacy parameters tends to 0 as the size of the game gets large, and
  2. In any such game, for any discount factor delta, as the size of the game gets large, the set of equilibria of the repeated game collapse to the set of equilibria of the stage game. In other words, there are no "folk theorem equilibria" -- only the equilibria that already existed in the one shot game. 
This could be interpreted in a couple of ways. On the one hand, this means that in large games, it might be harder to sustain cooperation (which is a negative result). On the other hand, since it shrinks the set of equilibria, it means that adding noise to the signaling structure in a large game generically improves the price of anarchy over equilibria of the repeated game, which is a positive result. 

Friday, April 04, 2014

Lecture 10 -- Running Ascending Price Auctions that Make Sincere Bidding an Ex-Post Dominant Strategy

In the 10th lecture in our privacy and mechanism design class, we consider the problem of running an ascending price auction. An ascending price auction is just a generalization of what you normally see as an "auction" on TV -- rather than submitting your valuation in some kind of one-shot protocol, the prices of the goods gradually rise, and you take turns with other bidders making bids on the goods as a function of the current prices.

Why would you want to run such an auction when the VCG mechanism already can provide welfare optimal outcomes for every social choice function, while making truthful reporting a dominant strategy? People quote a couple of reasons:

  1. It might be hard to actually report your full valuation: in principle, you need to figure out exactly your value for every bundle you might receive, and its difficult to pin down a number. In an ascending price auction, all you need to do is be able to point to your favorite good (or bundle of goods) that you would buy if the current prices were the final prices, which is often an easier task. 
  2. An ascending price auction can end without you having to reveal your full type. For example, in a single item second price auction, the highest bidder never has to reveal (even to the auctioneer) his value for the good -- only that it is higher than that of the second highest bidder. Hence, people might prefer such auctions for "privacy" reasons. 
In an ascending price auction, "truthful" reporting doesn't make sense, since nobody ever asks you to report your type. But we can ask for "sincere bidding", in which bidders truthfully bid on the item at each round that is their favorite, given the current prices. But there is a problem: we typically can't implement sincere bidding as a dominant strategy, because of the problem of threats. Consider the following simple example:

Suppose we have two unit demand bidders 1 and 2, and two goods for sale a and b. We have v_{1,a} = 1, v_{1,b} = epsilon and v_{2,a} = 1/2, v_{2, b} = 1/2 - \epsilon. Suppose moreover that bidder 2 takes the following strategy: "Bid on good a. If bidder 1 bids on good a, then outbid him on whatever he bids on until the price is > 1.'' Against this strategy, bidder 1 cannot obtain non-negative utility if he bids on his favorite good (a), and so his best response is to place an insincere bid on good 2. Moreover, bidder 2 has a clear motivation to take this threatening position -- he obtains substantially higher payoff than if players followed sincere bidding, since he gets his most preferred good without any competition. As a result of instances like these, typically ascending price auctions can implement sincere bidding at best as an (ex-post) Nash equilibirum. 

In this lecture, we talk about how to implement an ascending auction such that the prices are differentially private in the bidding strategies of the players (and the allocation in the end is jointly differentially private). This fixes two of the problems above:
  1. The privacy guaranteed by the ascending price auction is no longer hand-wavy and qualitative, but rather precise and quantitative. 
  2. We get sincere bidding as an asymptotic ex-post dominant strategy for all players.
To get this result, we need only a mild large-market assumption: that the "supply" of each good is modestly large compared to the number of different types of goods -- but crucially we need to assume nothing about how bidder preferences are generated. 

The intuition, which we will appeal to again later, is that by running the auction privately, we have eliminated the possibility that players can distort incentives by threatening each other.