Amelie Marian is visiting Webdam from Tuesday 1 September to Wednesday 30 September 2009 and from Tuesday 1 December to Thursday 31 December. She is an assistant professor at Rutgers University, New Jersey, USA. She will present her work on rating prediction using review texts Friday 4 December at 2pm in the meeting room G008.
Title: Beyond the Stars: Improving Rating Predictions using Review Text Content
Abstract: Online reviews are an important asset for users deciding to buy a product, see a movie, or go to a restaurant, as well as for businesses tracking user feedback. However, most reviews are written in a free-text format, and are therefore difficult for computer systems to understand, analyze, and aggregate. One consequence of this lack of structure is that searching text reviews is often frustrating for users; keyword searches typically do not provide good results as the same keywords routinely appear in good and in bad reviews. User experience would be greatly improved if the structure and sentiment information conveyed in the content of the reviews were taken into account. Our work focuses on identifying this structure and sentiment information from free-text reviews, and using this knowledge to improve user experience in accessing reviews. Specifically, we focused on improving recommendation accuracy in a restaurant review scenario.
We report on our classification effort, and on the insight on user-reviewing behavior that we gained in the process. We propose new ad-hoc and regression-based recommendation measures, that both take into account the textual component of user reviews. Our results show that using textual information results in better general or personalized restaurant score predictions than those derived from the numerical star ratings given by the users.
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Visitors
Yannis Papakonstantinou is visiting Webdam from Thursday 15 October to Friday 16 October 2009. He is a professor at the Computer Science and Engineering University of California, San Diego.
He will present his work on Database-Driven Web Applications Friday at 2:00pm in the meeting room G008.
Title: Do-It-Yourself Custom Database-Driven Web Applications
Abstract: UCSD’s app2you project (commercialized as app2you.com) and its successor FORWARD project belong to the emerging space of Do-It-Yourself (DIY), custom, hosted, database-driven web application platforms that empower non-programmer business process owners to rapidly and cheaply create and evolve applications customized to their organizations’ data and process needs.
Generally DIY application platforms provide an application design facility (also called application specification mechanism) where the application owner (also called process owner and business architect) specifies the application by manipulating visible aspects of it or by setting configuration options. A DIY platform must maximize the following two metrics: First, how wide is its application scope, that is, what computation,
collaboration on a process, and pages (presentation) can be achieved by applications specified using the platform’s design facility? Second, how easy is the specification of an application using the platform’s design facilities? The two metrics present an inherent tradeoff.
This talk focuses on human-centric database-driven web applications.
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Visitors
Francois Bancilhon is visiting Webdam Monday 4 May 2009. He is currently working on creation of PACMAN, a cooperative R&D project, based in Paris and focused on mobile Internet applications
He will present the PACMAN project at 2:00pm in the meeting room of building G.
Title: The PACMAN project
Summary: PACMAN is an r&d project submitted to the last call for projects (March-April 2009) of the Systematic and Cap Digital Competitivity Clusters.
The participants of the project are Agence France Presse, Alcaltel-Lucent, Bearstech, Dexxon, Haploid, INRIA (Arles and Indes projects), LIP6 (SMA and SPR projects), Mandriva, Streamezzo, and the City of Paris.
The project is focused on Mobile Internet Applications. It considers that the hardware/software platform for mobility is the Smartphone (i.e., iPhoneOS, Android, Windows Mobile, Symbian and WebOS).
The objective of the project is to deliver a set of technologies supporting mobile application development, to validate the use of these technologies by a significant set of mobile applications and to distribute these applications through and on line store (PacStore). Technologies include development and runtime tools and middleware. One of the key problems addressed by the project is that of portability (a single code for the same application running on different Smartphones).
Applications targeted by the project include social applications, training application, multi-player games and ubiquitous applications.
Short Bio: François Bancilhon is currently working on creation of PACMAN, a cooperative R&D project, based in Paris and focused on mobile Internet applications. Before this, he was the chairman and CEO of Mandriva (formerly Mandrakesoft), one of the top world Linux publishers. Prior to Mandriva, he has founded and/or managed several software startups in France and in the US. Before becoming an entrepreneur, François was a researcher and a university professor, in France and the US, specializing in database technology. François holds an engineering degree from the École des Mines de Paris, a PhD from the University of Michigan and a Doctorate from the University of Paris XI.
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Social Networks, Visitors
Werner Nutt is visiting Webdam from Monday 20 April to Friday 24 April 2009. He is a professor at the Faculty of Computer Science at the Free University of Bozen-Bolzano.
He will present his work on containment of conjunctive queries over databases with null values Friday at 2:00pm in the meeting room G008.
Title : Containment of Conjunctive Queries over Databases with Null Values (Joint work with Carles Farre, Ernest Teniente, and Toni Urpi, UPC Barcelona)
Summary : Intuitively, one query “contains” another query if it is more general than the other query. Query containment is a key topic in database theory, which was originally motivated as a foundation of query optimisation, but has also other applications, such as integrity checking and information integration.
The containment problem has been studied for many different types of queries. The work so far, however, has never considered the effect of SQL style null values, although they are ubiquitous in real world data and queries have to process them.
In this talk we discuss in which ways null-containment, that is, containment in the presence of null values, differs from the non-null case. We consider conjunctive queries, which are essentially single block SQL queries. We show that null-containment, as in the non-null case, is NP-complete for boolean queries, which return only yes or no, while the situation becomes different from the classical case for queries that output data. We also discuss sufficient, but non-necessary criteria for null-containment, special cases with polynomial complexity, the effect of “is null” tests, as well as null-containment for richer classes of queries where comparisons or unions are allowed.
Short Bio : Werner Nutt is a professor at the Faculty of Computer Science at the Free University of Bozen-Bolzano in the Italian Alps (since 2005). He obtained a PhD and a habilitation from the university of Saarbruecken, was a visiting associate professor in Jerusalem (1997-2000) and a reader at Heriot-Watt University in Edinburgh (2000-2005). His research interests are in Artificial Intelligence and Databases, with a focus on Description Logics, Information Integration and Incomplete Information.
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Database Theory, Visitors
Bruno Marnette is visiting Webdam Thursday 16 April 2009. He is a phD student at the computing laboratory of the Oxford University.
He will present his work on schema mappings Thursday at 10:30am at ENS Cachan in LSV-library.
Title : Schema-Mappings: From Termination To Tractability
Summary : Data-Exchange is the problem of creating automatically a new database while integrating the information encoded in (1) a given source database and (2) a high-level specification called schema-mapping. After investing the general properties of (generalised) schema-mappings and their semantics, I will introduce in this talk a new sufficient condition TOC for polynomial data-complexity. This criteria TOC generalizes strictly and substantially the best previously-known criteria called Weak-Acyclicity and relies on the termination of (a refinement of) a known procedure called Oblivious Chase. While TOC is RE-complete, I will finally present a more restrictive criteria SwA (for Super-weak Acylicity) that can be decided in polynomial time while generalizing already substantially the notion of Weak Acyclicity.
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Database Theory, Visitors
Sonja Buchegger is visiting Webdam Monday 9 March 2009. She is a senior research scientist at the Deutsche Telekom Laboratories, Berlin.
She will present Peerson, a P2P Social Networks at 2:00pm in the meeting room of building N.
Title : Peerson: P2P Social Networks
Summary : Online Social Networks like Facebook, MySpace, Xing, etc. have become extremely popular. Yet they have some limitations that we want to overcome for a next generation of social networks: privacy concerns and requirements of Internet connectivity, both of which are due to web-based applications on a central site whose owner has access to all data.
To overcome these limitations, we envision a paradigm shift from client-server to a peer-to-peer infrastructure coupled with encryption so that users keep control of their data and can use the social network also locally, without Internet access. This shift gives rise to many research questions intersecting networking, security, distributed systems and social network analysis, leading to a better understanding of how technology can support social interactions.
Short Bio : Sonja Buchegger is a senior research scientist at the Deutsche Telekom Laboratories, Berlin. In 2005 and 2006, she was a post-doctoral scholar at the University of California at Berkeley, School of Information. She received her Ph.D. in Communication Systems from EPFL, Switzerland, in 2004, a graduate degree in Computer Science in 1999, and undergraduate degrees in Computer Science in 1996 and in Business Administration in 1995 from the University of Klagenfurt, Austria. In 2003 and 2004 she was a research and teaching assistant at EPFL and from 1999 to 2003 she worked at the IBM Zurich Research Laboratory in the Network Technologies Group. Her current research interests are in social, economics, and security aspects of self-organized networks.
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Social Networks, Visitors
Diego Calvanese is visiting Webdam from Monday 23 February to Friday 27 February 2009. He is a professor at the Faculty of Computer Science at the Free University of Bozen-Bolzano.
He will present his work on Ontology-Based Data Access and Data Integration Wednesday at 2:00pm in the meeting room N107.
Title : Ontology-Based Data Access and Data Integration
Summary :Ontologies provide a conceptualization of a domain of interest. Nowadays, they are typically represented in terms of Description Logics, and are seen as the key technology used to describe the semantics of information at various sites. The idea of using ontologies as a conceptual view over data repositories is becoming more and more popular. In order for this idea to become widespread in standard applications, it is fundamental that the conceptual layer through which the underlying data layer is accessed does not introduce a significant overhead in dealing with the data. Based on these observations, in recent years techniques to access data sources through a conceptual layer built on top of them have been developed, and the computational complexity of answering queries over ontologies, measured in the size of the underlying data, has been studied. In the talk we will present the general ideas underlying ontology based data access and integration, and will discuss the tradeoff between expressive power of the ontology language, and efficiency in query processing. Specifically, we will address the possibility of delegating query processing in ontology based data access to a relational database engine and will also present the QuOnto system, implementing this approach.
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Database Theory, Ontologies, Visitors
Werner Nutt and Diego Calvanese from Free U. of Bozen-Bolzano will both come for short visits.
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Visitors
