Webdam Project

Webdam and the Fox European project will organize a Dagstuhl workshop on Foundations of Distributed Data Management, 17-21 October 2011.
Please, if you want to attend, block the dates and stay tuned.

Events, News Dissemination, Workshop

Yannis Kastis gave a presentation of Webdam Current Research Directions, Wednesday 16 june 2010, at the Yearly LSV Meeting “Barbizon 2010″.

News Dissemination, Report

Balder ten Cate is visiting Webdam from Monday 5 July to Saturday 10 july 2009 and from Saturday 17 July to Saturday 24 July. He is a postdoctoral researcher in the database theory group at UC Santa Cruz.

News Visitors

Webdam is very happy that Bruno Marnette, who previously visited us for 2 months, joined the team for a post doc.

Bruno Marnette was doing his PhD at Oxford University under the direction of Georg Gottlob.

News Members

1. Fabian Suchanek who recently joined Webdam received the Honorable Mention at ACM Sigmod  Dissertion Awards.
2. Yannis Papakonstantinou will be visiting Webdam for 3 weeks in July.
3. The BDA summer school co-organized by Webdam is happening now in Les Houches. An important part of the Webdam textbook is being tested.

News Members, SummerSchool, Visitors

Gerome Miklau is visiting Webdam Wednesday 2 June at 2pm. He is an Assistant Professor at the Computer Science Department of University of Massachusetts, Amherst. He will present his work on differential privacy in the meeting room of LSV at ENS Cachan.

Title: Optimizing Linear Counting Queries Under Differential Privacy

Abstract: Differential privacy is a rigorous privacy standard that protects against powerful adversaries, offers precise accuracy guarantees, and has been successfully applied to a range of data analysis tasks. When differential privacy is satisfied, participants in a dataset enjoy the compelling assurance that information released about the dataset is virtually indistinguishable whether or not their personal data is included.

Differential privacy is achieved by introducing randomness into query answers. The original algorithm for achieving differential privacy, commonly called the Laplace mechanism, returns the true answer after the addition of random noise drawn from a Laplace distribution. If an analyst requires only the answer to a single query about the database, then the Laplace mechanism is known to be optimal. But the Laplace mechanism can be highly suboptimal when a set of correlated queries are submitted, and despite much recent work, optimal strategies for answering a collection of correlated queries are not known in general.

In this talk I will review the basic principles of differential privacy and then describe the “matrix mechanism”, a new algorithm for answering a workload of predicate counting queries. Given a workload, the mechanism first requests answers to a different set of queries, called a query strategy, which are answered using the standard Laplace mechanism. Noisy answers to the workload queries are then derived from the noisy answers to the strategy queries.

When the strategy queries are chosen appropriately, this two stage process increases accuracy (with no cost in privacy) by answering the workload queries using a more complex, correlated noise distribution. I will show that two recently-proposed algorithms, which provide accurate answers for the set of all range queries, can be seen as instances of the matrix mechanism. I will then present results on optimally choosing the query strategy to minimize the error for any given workload.

This talk is based on forthcoming work that will appear in PODS 2010 and VLDB 2010, and is joint with Chao Li, Michael Hay, Vibhor Rastogi, Andrew McGregor, and Dan Suciu.

News Visitors

Webdam is very happy to announce that Meghyn Bienvenu is joining the project.

She is currently at University of Bremen. She is ranked 1st at CNRS, candidate at LRI, University Orsay.

News Members

Serge Abiteboul co-organized the workshop “Enabling Holistic Approaches to Business Process Lifecycle Management”.

He also had an invited presentation on “Objects and Data” at another Dagstuhl Workshop that was happening in parallel, on “Relationships, Objects, Roles, and Queries in Modern Programming Languages”

News Dissemination, Workshop

The webdam team is very happy to announce that Victor Vianu, who was already collaborating actively with us, will join us for 14 months, joining first of July. Victor will be in sabbatical first then leave from UCSD, where he is professor.

This great hiring, as well as the one of Fabian, demonstrates that web data management, the topic of the project, is an attractive research topic.

News Members

Serge Abiteboul attended the Datalog 2.0 Conference, at Oxford. He presented a survey of works around AXML and Webdam (Abiteboul10WSOxford)

Ioana Manolescu organized a very interesting panel at the last Conference on Extending Database Technology in Lausanne (joint with International Conference on Database Theory). Serge was a member of the panel (Manolescu10EDBTPanel, Abiteboul10EDBTPanel). Recent Webdam works on probabilistic XML was also presented at ICDT.

Serge is co-organizer of the Dagstuhl workshop Enabling Holistic Approaches to Business Process Lifecycle Management.

It is nice to see that topics that are important for Webdam are gaining popularity:

• Datalog that was not very fashionable is striking back.
• Data-centric workflows are one of the topics of the Dagstuhl workshop.
• In general there is renewed interest for distributed data management.

News Dissemination, Workshop