Archive for the ‘event’ Category

Social Computing @ UCL-CS

Tuesday, November 11th, 2008
Today was the long-awaited follow up to the first introductory mobisys seminar. The theme today was on the social computing research going on in the group, or, more specifically, the overlap between social and pervasive research. Only a handful of speakers gave their pitch, since we have heard from Daniele (slides), Sonia, and myself in the last few weeks. The slides from the session are below:
Social Computing Research
View SlideShare presentation or Upload your own. (tags: researchsocial computingucllondonucl)

We followed up the pitches with a brainstorming session on the future of mobisys seminars and collaborative work. Lots of great ideas emerged: we are looking forward to incorporating them into our seminar series in the near future!

Tutorials at RecSys 2008

Friday, October 24th, 2008

Yesterday was the first day of RecSys 2008, and was dedicated to three very interesting tutorials:

1. Robust Recommender Systems. Robin Burke introduced the wide range of attacks that typical collaborative filtering algorithms are vulnerable to; scenarios that arise when people attempt to force, rather than express, opinions. An attack was strictly defined as a set of profiles intending to obtain excessive influence on others, which can be aimed at pushing (making recommendation more likely) or nuking (i.e. recommendation less likely) items. His talk was an interesting blend of attack strategies, knowledge that attackers need to have, and a high-level description of approaches aiming at preventing or fixing the system when attacked. Of course, there are strong overlaps between this work and work in other areas (p2p trust, adversarial information retrieval, search engine spam..); I particularly like this area as pushes the point that recommender systems are about people/dynamic datasets, and not just prediction.

2. Recent Progress in Collaborative Filtering. Yehuda Koren (who has recently moved from AT&T to Yahoo! Research) gave a tutorial about the leading approaches in the Netflix prize competition. The techniques he described blend matrix factorisation and neighbourhood models, and include a number of other factors (such as user biases and time) that result in techniques that have multiple-billions of parameters (and the resulting ranking of team BellKor in the competition). His work is remarkable and worthy of the progress prizes he has been awarded thus far. He also explored alternative techniques of evaluating recommender systems, explaining his take on evaluating top-N recommendation lists.

3. Context-Aware Recommendations. Gedas Adomavicius and Alex Tuzhilin introduced their work on incorporating context into recommender systems, including pre-, post-, and hybrid-filtering of recommendation algorithm results based on user context. A running example that was repeated throughout the tutorial was going to the theatre with your girlfriend on the weekend: if you always watch comedy, then your recommendations can be filtered to match what you did in previous instances of the same context (i.e. you can be recommended comedy). They have done a lot of cool stuff on multi-dimensional recommenders, extending the common rating scales into cubes of ratings, and stressed more than once that this is virgin territory. Their work is also impressive, but raised a few questions. For example, should context be described by a well-enumerated taxonomy? Moreover, if you always watch comedy at the theatre with your girlfriend on weekends, then why should you need a recommender system in the first place (especially a collaborative one- what happened to serendipity or diversity)? They have a number of papers that are worth reading before trying to answer these questions!

MobiSys: UCL and Birkbeck Research

Tuesday, October 14th, 2008

The mobisys seminar series had its first presentation of the (academic) year today. We decided to slightly change the format. Instead of having a single speaker present for 45 minutes, we would have short research-pitches; that way, the various old and new group members could introduce themselves and their work to each other.  We were also very happy to have Birkbeck researchers present, since a lot of their work has strong overlaps with what is going on in the mobisys group.

By last night, I had about 19 speakers ready to present: way too many! So I decided to break the minute-madness presentations into two sessions. The first was today, centred around the theme of pervasive computing. The second session, broadly categorised as social computing, will be in the coming weeks.

Each speaker had 4 minutes to introduce and overview their work (and were promptly interrupted by my annoying alarm clock sound if they went over): the slides are below. The whole idea of these sessions is to highlight how many people are working on similar problems and to foster discussion (perhaps in an effort to combat “phd depression?”)- unfortunately we did not have much time for the latter today, and I hope that we will in future events.

We rounded up the session with an overview of current research projects going on in the respective departments by Steve Hailes and George Roussos.

MobiSys Group Presentation
View SlideShare presentation or Upload your own. (tags: networks sensors)

KDD-08 video lectures

Tuesday, October 7th, 2008

KDD-08 videos include:


Analysis of Social Networks using Ucinet and Siena @ Ox

Thursday, October 2nd, 2008

A one-week workshop on Analysis of Social Networks using Ucinet and Siena, taught by Martin Everett and Tom Snijders, will be held in Oxford, December 15-19, 2008. Registration will be opened soon at the website of the Oxford Spring School. It will be possible to register independently for the Ucinet part (Monday-Tuesday, taught by Martin Everett) and for the Siena part (Wednesday-Friday, taught by Tom Snijders). The program is available at

Machine Learning Applications to Music

Wednesday, October 1st, 2008

Louis gave a very interesting talk about his research on applying machine learning to music. Interestingly, among other things, he discussed two issues of music retrievial:

1) Does the use tags improve retrieval algorithms? In my opinion, the answer is a qualified yes. Case in point: this month at Recsys, Licia and Valentina will present an effective  way of retrieving items (e.g., music files) . Their technique exploits two types of similarity  (item similarity and user similarity), both of which are computed only from (user-specified) tags.  Check section 3 of this paper (short description) and their RecSys paper (complete description).

2) Exsting retrievial algorithms learn your music taste and assume  that it does not change over time. What if you change your taste? That’s a question Neal will answer at, again, RecSys this month. Check his paper.

Ubicomp 2008

Monday, September 29th, 2008

Many blogs have been covering Ubicomp and, a couple of days ago, I promised to write down my own coverage. Here you go ;-)

The first day I attended the Automated Journeys workshop organized by Arianna Bassoli (who gave a talk at UCL a while back), Johanna Brewer (whose recent work has been covered here; for more, check her blog), and . The workshop’s format was not  traditional. As part of the workshop, we went out and had lunch :-), and, while doing so, we observed how people in Seoul use technologies.  Then, we came back and, through group discussions and hands-on design brainstorming sessions, we produced  4 envisagements that  critically reflected on technological futures. It was very engaging! I hope other workshops will replicate/mutate this format. I wished I could attend at least two of the  other workshops on offer: Ubiquitous Systems Evaluation partly organized by Chris Kray (I am in debt with him, and he knows why ;-)) and Devices that Alter Perception partly organized by Carson Reynolds.

At Ubicomp, the speakers did not suffer from powerpoint karaoke syndrome, and their slides were generally  well-designed – less text, more images. That is largely because the ubicomp’s community is made of design-conscious (CHI) researchers. Few talks are already available on slideshare.

Here are few papers I personally found intriguing because of their algorithms, their evaluation, or their interesting ideas. At the end of this post, I’ll point to few datasets that have been used and can be of interest ;-)

1. Algorithms

Navigate Like a Cabbie: Probabilistic Reasoning from Observed Context-Aware Behavior. Brian D. Ziebart showed a new way of making route predictions. He used a probabilistic model  presented at AAAI “Maximum Entropy Inverse Reinforcement Learning“.  Interestingly, he showed that the model works upon data that is noisy and imperfect.

Pedestrian Localisation for Indoor Environments. Oliver Woodman proposed a way of  tracking people indoor. Oliver and Robert showed how to combine a foot-mounted unit, a building model, and a particle filter to track people in a building. They experimentally showed that users can be effectively tracked within 1m without knowing their initial positions. Great results! It’s a paper well worth reading!

Discovery of Activity Patterns using Topic Models. Bernt Schiele presented a new method for recognizing a person’s activities from wearable sensors.  This method adapts probabilistic topic models and has been shown to recognize daily routines without user annotation.  One of Bernt’s students had an interesting poster on detecting location transitition using sensor data (pdf).

2. Evaluation

A couple of papers (including the great work done by Matthew Lee)  used a method called the Wizard of Oz evaluation. The general idea is to simulate those parts of the system (e.g., speech recognition) that require most effort in terms of development or to assess the suitability of your interface(see “Wizard of Oz studies – why and how” (pdf) for more).

Flowers or a Robot Army? Encouraging Awareness & Activity with Personal, Mobile Displays by Sunny Consolvo et al.  They designed a system that makes it possible for mobile users to self-monitor their physical activities and conducted a greatly designed 3-month field experiment.

Reflecting on the Invisible: Understanding End-User Perceptions of Ubiquitous Computing (pdf). Erika Shehan Poole detailed end-user perceptions of RFID technology using an interesting qualitative method that combines structured interviews and photo elicitation excercises. Erika and her mates show that, by using this method, one is able to uncover perceptions that are often difficult for study participants to verbalize.  One of her findings: many people believed that RFID can be used to remotely tract the location of tagged objects, people, or animals!

3. Interesting Ideas

Bookisheet: Bendable Device for Browsing Content Using the Metaphor of Leafing Through the Pages. Trash your mouse. Jun-ichiro Watanabe presented a VERY promising interface (a book made of two thin plastic sheets and bend sensors) with which  a user can easily scroll digital content such as photos. The user  does so by simply bending one side of the sheet or the other.

Towards the Automated Social Analysis of Situated Speech Data. To automatically understand individual and group behavior, Danny Wyatt et al. recorded the coversational dynamics of 24 people over 6 months. They did so using privacy-sensitive techniques. By using this type of studies, researchers may well  gain broad sociological insights.

The Potential for Location-Aware Power ManagementRobert Harle showed how to dinamically optimize the energy consumption of an office. Very interesting problem-driven research!

Accessible Contextual Information for Urban Orientation
. Jason Stewart  presented a prototype of a location-based  service with which mobile users share content (see their project’s website)

Enhanced Shopping: A Dynamic Map in a Retail Store.  Alexander Meschtscherjakov  presented a prototype for mobile phones that displays  customer activities (e.g., customer flow) inside a shopping mall

Spyn: Augmenting Knitting to Support Storytelling and Reflection (pdf). Daniela K. Rosner‘s presentation was masterfully designed! She walked us through her expirience of designing Spyn – a system for knitters to record, playback, and share information involved in the creation of their hand-knit artifacts. She showed how her system enriches the knitter’s craft

Picture This! Film assembly using toy gestures. Cati Vaucelle (who keeps a cool blog) presented a new input device embedded in children’s toys for video composition.  As they play with the toys to act out a story, children conduct film assembly.

4. Datasets

Understanding Mobility Based on GPS Data by et al. used GPS logs of 65 people over 10 months (the largest dataset in the community!) to evaluate a new way of  inferring people’s motion modes from their GPS logs

Accurate Activity Recognition in a Home Setting (pdf) by Tim van Kasteren et al. used 28 days of sensor data about one person @ home and corresponding annotations of his activities (e.g., toileting, showering, etc.) to evaluate a new method for recognizing activities from sensor data.

Discovery of Activity Patterns using Topic Models by Tam Huynh et al. used 16 days of sensor data from a man who was carrying  2 wearable sensors to test their method for automatically recognizing activities (e.g., dinner, commuting, lunch, office work) from sensor data.

On Using Existing Time-Use Study Data for Ubiquitous Compting Applications by Kurt Partridge and Philippe Golle how to use data (e.g. people’s activities and locations) that has been collected by governments and commercial institutions to evaluate ubicomp systems.

The Potential for Location-Aware Power Management by Rober Harletested on location data of 40 people in 50-room office building for 60 working days his proposed strategies for dinamically optimizing the energy consumption of an office.


“Making Mobile Raters Stick to their Word ” @ Ubicomp

Monday, September 22nd, 2008

In few hours I will present MobiRate. Fortunately, the slides are ready ! See them next. A short description follows.

P.S. I’ll blog about Ubicomp shortly. For now, look at the great coverage by Albrecht Schmidt  ;-)


View SlideShare presentation or Upload your own. (tags: trust systems)

Q&A Session (at the conference):

Q> You have shown that MobiRate effectively protects against *indepedent* malicious individuals. What if  malicious individuals collude?
A> Colluding malicious peole will not be able to tweak  ratings because they cannot produce fake crypto material. However, if malicious people collude, one may well run into updating problems. Phones update their ratings  while they move and, consequently, there are   time windows in which ratings are not up-to-date. During those time-windows, colluding people may succeed in attacking the communities they are in  (e.g., in flooding the system with spam content).

Q>  Phones that run MobiRate audit each other. Are their users aware of that?
A> We have assumed that, in downloading and running MobiRate, people silently agree with  the possibility of their phones being “auditors”. However, people should be able to step back and refuse to be auditors at times; for example, whenever they are running out of battery. This feature should be definetely
included in the next version of MobiRate.

Q> Your solution is general, in that, it is able to collect and store not only user ratings but also user activities!
True.  Instead of monitoring ratings, one could force people in keeping a record of their activities. Before deploying MobiRate, we should carefully think about its misuses and try to prevent them. A good starting point could be to understand how “historical misuses of technology can be studied to be avoided in the future” (link)

Short Description of MobiRate:


Talks @ OII

Friday, September 12th, 2008

Two interesting upcoming events at the Oxfor Internet Institute:

  • 23 September: Tracking the Internet into the 21st Century (Tuesday , 11:00 – 12:00)
    by Vint Cerf! Chief Internet Evangelist for Google
  • 20 October: Making Sense of YouTube (Monday, 15:00 – 16:00)
    by Jean Burgess
    “This presentation reports on a recent study of YouTube that relied principally on a survey of 4300 of the most ‘popular’ videos… The analysis produced new knowledge about the extent of particular uses of the platform (such as vlogging, political commentary, or the ‘distribution’ of broadcast content); and the relationship between different modes of ‘audience’ engagement (commenting, responding, rating) and particular content genres. “

Future Directions of IR: Event in London

Friday, September 5th, 2008

From the Call for Participation:

The 2nd BCS-IRSG Symposium on Future Directions of Information Access
in conjunction with Search Solutions 2008

22nd and 23rd  of September 2008
London, UK

The FDIA symposium series aims to promote and encourage researchers in
the early stages of their careers within the field of Information
Retrieval. The symposium provides a unique platform for young researchers
to get together and discuss their research in a friendly environment and
learn more about the field and their peers.

At the first symposium held last year, the aim was to provide a forum
where future directions of information access can be presented and
discussed in an open and friendly environment. The focus of the 2nd
Symposium on Future Directions in Information Access will be to continue
this theme by dedicating an entire day to the discussion and promotion of
such research in a fun, entertaining and exciting way.

Why future directions, because we want to encourage submission that focus
on the early research such as pilot studies, presenting challenges and
future opportunities, conceptual and theoretical work, and the
contributions from doctoral work.

Why Information Access, because it captures the broader ideas of
information retrieval, storage and management to include interaction and

For the detailed program and how to register please visit the FDIA

Trust Meeting at Secrypt

Sunday, July 27th, 2008

We presented an invited paper (pdf) at a meeting on how to manage trust in percom at Secrypt. The paper is about how to offer digital content to mobile users by combining tagging with reputation systems (previous post). Here is my presentation:

Few words on:

1) The meeting (3 sessions)
Session 1
Existing reputation systems often set initial user’s reputation to a fixed value (e.g., 0.5 if reputation is expressed on a scale [0,1]). Christian proposed interesting ways for setting initial trust other than fixing ad-hoc values. Juri Luca of L3S followed by presenting a review of policy languages for trust management. Ioanna of Uni of Nicosia concluded the first session by showing a way of formalizing trust relationships that change over time.

Session 2
I started the session (no more self-publicity ;-)). Zhen Yan followed and showed a way of managing trust in autonomic computing for healthcare. Finally, Andre concluded the second section by putting forward a secure interface for e-voting terminals – he documented a very interesting evaluation in his well-written paper.

Session 3
Gabriele started off by presenting a new way of assigning weights to user ratings. This way allows for personalizing ratings, and that is beneficial because it makes it possible for two individuals
to have different opinions about the trustworthiness of the same person (which may well happen in reality). My tip: this research may well be complemented by “sentiment analysis” (e.g., see this paper in  pdf). Ben Aziz of CCLRC concluded the third session and presented a reputation system for grid computing.

A big thanks goes to Mari for wonderfully organizing and chairing the three sessions ;-)

2) The conference (3 points)

  • Petteri & his working mates of VTT collected 40K ideas for future mobile services from passionate users and stored them in the “idea database” (InnoBar is the most recent of those databases, which include: Mefi, Owela, and Idealiiike – the last two only in finnish). One interesting problem is how to bring order in that long list of ideas. Of course, one way for doing so is to resort to the wisdom of the crowd – during the Q&A session, Petteri told me that it’s difficult to have users rate ideas. How about having a crowd of paid (technology) experts? (paper: ON EXPLORING CONSUMERS’ TECHNOLOGY FORESIGHT CAPABILITIES)
  • Mari Ervasti studied which factors facilitate the acceptance of mobile services by proposing a modified version of the Technology Acceptance Model (paper: ADOPTION OF MOBILE SERVICES IN FINLAND - Conceptual Model and Application-based Case Study).
  • Niklas Eriksson presented three websites they developed for enabling mobile tourism services: MobiPortal, TraveLog, and MobiTour (paper: MOBILE TOURISM SERVICES – Experiences from Three Services on Trial).

Pls feel free to add whatever I’ve forgotten to mention in the comment section below. Cheers!

IFIPTM Monday workshops (CAT, W2Trust)

Monday, June 23rd, 2008

The Monday workshop sessions of IFIPTM 2008 were a combination of the second workshop on Context-awareness and trust (CAT) and first workshop on Web 2.0 trust (W2Trust). See the W2Trust website for the full list of papers. In this post, we summarize what we saw.



Friday, June 20th, 2008

Fourth International Workshop on the Value of Security through Collaboration (SECOVAL 2008)
part of SECURECOMM’08 in cooperation with ACM and CREATE-NET
September 22nd, Istanbul, Turkey
Submission Deadline: July 10, 2008

Intl Workshop on Trust in Mobile Environments

Wednesday, June 18th, 2008

Yesterday was the first International Workshop on Trust in Mobile Environments (TIME 2008), co-located with the IFIPTM 08 conference in Trondheim, Norway. The workshop merged with the Workshop on Sustaining Privacy in Autonomous Collaborative Environments (SPACE), and consisted of three sessions. Here is a brief summary on what we saw: (more…)

Conference on Reputation

Wednesday, June 4th, 2008

First International Conference on Reputation

What: Work on Reputation from a multidisciplinary standpoint

Where: Tuscany, Italy

When: March 2009