Dr. David Portabella

PhD in Computer Science at the Artificial Intelligence Laboratory at EPFL completed in 2007.
In 2008 we have been awarded the Innogrant price to launch a start-up, DB4ALL, together with the EPFL Database laboratory.

Postal Address:
    EPFL - IC - IIF - LBD
    Station 14
    CH - 1015 Lausanne
    Switzerland

Phone and Fax:
    Tel: +41216936707
    Fax: +41216935195

Email:
    david.portabella@gmail.com
    david@portabella.name

My interest in computer science focus on decision support systems (DSS), web information extraction and databases.
I am also interested in natural language processing and understanding, expert systems, multimodal interaction and the semantic web.

Get a copy of my resume (curriculum).

Go to: PhD, Publications, Projects, Courses, Student Projects, Personal (photos and adventures) :)
Check also my Blog and my Linkedin profile.

PhD

Title: Improving User Confidence in Decision Support Systems for Electronic Catalogs.

Abstract:
Decision support systems for electronic catalogs assist users in making the right decision from a set of possible choices. Common examples of decision making include shopping, deciding where to go for holidays, or deciding your vote in an election. Current research in the field is mainly focused on improving such systems in terms of decision accuracy, i.e. the ratio of correct decisions out of the total number of decisions taken. However, it has been widely recognized recently that another important dimension to consider is how to improve decision confidence, i.e . the certainty of the decision maker that she has made the best decision.

We first review multi-attribute decision theory --the underlying framework for electronic catalogs-- and present the state-of-the-art research in e-catalogs. We then describe objective and subjective measures to evaluate such systems, and propose a system baseline for achieving more accurate and meaningful comparative evaluations.

We propose a framework to study the building of decision confidence within the query-feedback search interaction model, and use it to compare different types of system feedback proposed in the literature. We argue that different types of system feedback based on constraints ( e.g. conflict and corrective feedback), even if not novel as such, can be combined in order to improve decision confidence. This claim is further validated by simulations and experimental evaluation comparing constraint-based feedback to ranked list feedback.

Take-Away message:
Conflict and corrective feedback are the most promising types of feedback for decision confidence building. This claim is supported by experimental evaluation in the case of ranked list feedback compared to conflict and corrective feedback. In typical situations where there is a mismatch between what the decision maker wants and what is it in the catalog, Confidence Building Tradeoff Explanations (CBTE) provide a clear trade-off question to help the user make a good decision through the global relaxation set, and provides evidence for building decision confidence through the minimal conflict set and the local relaxation set.
In the same experimental evaluation, we saw that CBTE system feedback incited more participants to make more challenging queries, and thus to state more accurate objectives rather than mean objectives. This is a very beneficial behavior because DSSECs can better help them if users state precise objectives.

Download:

Download full dissertation
Citation: Text, Bibtex
Public presentation: Slides in PDF, Slides with attached videos (PowerPoint)
Video of the public presentation
Example video of the normative way of making accurate decision (which does not build decision confidence)
ECatalog: A decision support system that improves user decision confidence.
Includes also our complete User Study software and set-up.

Publications

Portabella Clotet, David and Rajman, Martin. Explicit Trade-off and Prospective Analysis in Electronic Catalogs. Workshop on Recommender Systems. European Conference on Artificial Intelligence. Riva del Garda, Italy, August 2006.
Portabella Clotet, David and Rajman, Martin. Explicit Passive Analysis in Electronic Catalogs. Proceedings of the National Conference on Artificial Intelligence, AAAI-06. Poster. Boston, July 2006.
Portabella Clotet, David and Pallotta, Vincenzo and Rajman, Martin. Systematic definition and assent to eContracts for Web Services. CoAla 2005 Workshop on Contract Architectures and Languages, Enschede, The Netherlands, November 2005. BibTeX Entry
D. Portabella and M. Rajman. A Dialogue-based Grounding mechanism and new Service Description Features for adapting Semantic (Web) Services to Personal Assistants. Technical Report No. ID: IC/2004/85, Swiss Federal Institute of Technology (EPFL), Lausanne (Switzerland), November, 2004. BibTeX Entry
Portabella D. The IM2.MDM demonstrator: a dialogue based interface for the meeting database. Poster. IM2 Summer Institute 2003, Centre de conférences du Régent, Crans-Montana, October 6-7-8.
Portabella D., Pallotta V., Rajman M., Ghorbel H., Vesely M., Bui T., Etxebarria A., .Derivation of a semantic knowledge base from existing language resources. Report IM2.MDM-11, January 2003 (Deliverable MDM.ONTO.D1)
Armstrong S., Clark A., Coray G., Georgescul M., Pallotta V., Popescu-Belis A., Portabella D., Rajman M., Starlander M., .Natural Language Queries on Natural Language Data: a Database of Meeting Dialogues. NLDB 2003 (8th International Conference on Applications of Natural Language to Information Systems), Burg/Cottbus, Germany, 2003. BibTeX Entry
D. Portabella, A. Febrer, A. Moreno. NaniTrans: A Speech Labeling tool. Proc. LREC'2000, Athens, 2000

Projects

2006 Mar, ECatalog: A decision support system that improves user decision confidence.
Includes also our complete User Study software and set-up.
The database of second-hand cars kindly provided by Comparis.ch can be downloaded here.
2005 Jun, RDP tutorial: Practical work: Rapid Dialogue Prototyping.
With Mirek Melichar and Martin Rajman.
2003 Speech dialogue, multimodality and Wizard of Oz experiments
2003 Oct: First version of multimodal RDP in java, with a demo for IM2.MDM
2003 Apr, A Wizard of Oz for VoiceXML
2003 RDP tutorial-2003.
With Alex Trutnev, Trung Bui and Martin Rajman.
2002 Dec, A multimodal extended VoiceXml demo for IM2.MDM
2001, Large Scale Semantic Resources. A Tool for browsing EDR
A Gui interface to browse the EDR Dictionary. The EDR Electronic Dictionary is a machine-tractable dictionary that catalogues the lexical knowledge of Japanese and English (the Word Dictionary, the Bilingual Dictionary, and the Co-occurrence Dictionary), and has unified thesaurus-like concept classifications (the Concept Dictionary) with corpus databases (the EDR Corpus).

Courses

I have been assistant in the following courses:

Cours de programation II, Undergraduates, Martin Rajman, Sumer Semester 2002 - 2003
The pong project
Cours de programation I, Undergraduates, Sam-Haroud, Winter Semester 2003 - 2004
Cours de programation II, Undergradutes, Martin Rajman, Sumer Semester 2003 - 2004
Natural Language Processing (TIDT), Doctoral School, Martin Rajman & Jean-Cédric Chappelier, Sumer Semester 2004-2005

Student Projects

I have supervised the following student projects:

Resume Extraction using Markov Logic. Laetitia Henriot. Winter semester 2007-2008.
Project co-upervised with Marita Ailomaa.
Digital Libraries (Nebis, Infoscience and The European Library). The Quang Nguyen. Summer semester 2006-2007.
Download report. Associated files available under demand (copyright from the European Library). Project co-upervised with Mirek Melichar.
Extending BitTorrent. Baptiste Dubuis. Winter semester 2006-2007.
Download report and presentation. Get the library at Sourceforge homepage.
Creating Installers for Java Applications. Asheesh Gulati. Winter semester 2006-2007.
Download report and associated files.
WebCatalog. Vincent Etter. Summer Semester 2005-2006. Get the library at Sourceforge homepage.
PDA Web Interface. Ramatou Abibou . Summer Sesmter 2005-2006.
Run-time transformation of java bytecode for Web Service invocation. Nadir Hadbi. Sumer semester 2004 - 2005.
Download report.
Assisting users to provide information required for a Web Service. Muriel Gumy. Sumer semester 2004 - 2005.
Download report. Project co-upervised with Ion Constantinescu.
Semantic Web scenarios. Vlad Tanasescu. Summer semester 2003 - 2004.
Integrating Speech in Web browsers. Alex Omar Prudencio Arispe. Summer semester 2002-2003.
Download report.

Keywords: decision support systems (DSS), web information extraction, databases, query filtering, cooperative answering in databases, recommender systems, case-based reasoning (CBR), collaborative filtering (CF), digital libraries (DL), information visualization seeking (InfoVis), conversational recommenders, decision theory, natural language processing and understanding, expert systems, multimodal interaction, semantic web.

Main website: http://david.portabella.name/
Last modified: January 9, 2008